TY  - CONF
AU  - Dančuo, Zorana
AU  - Kostić, Ivan
AU  - Kostić, Olivera
AU  - Bengin, Aleksandar
AU  - Vorotović, Goran
PY  - 2024
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/7386
PB  - Springer Nature Switzerland AG
T1  - Influence of Thickness Ratio on the Aerodynamic Characteristics of a Family of Hybrid Semielliptical Dolphin Airfoils
DO  - 10.1007/978-3-031-42041-2_1
ER  - 

@conference{
author = "Dančuo, Zorana and Kostić, Ivan and Kostić, Olivera and Bengin, Aleksandar and Vorotović, Goran",
year = "2024",
publisher = "Springer Nature Switzerland AG",
title = "Influence of Thickness Ratio on the Aerodynamic Characteristics of a Family of Hybrid Semielliptical Dolphin Airfoils",
doi = "10.1007/978-3-031-42041-2_1"
}

Dančuo, Z., Kostić, I., Kostić, O., Bengin, A.,& Vorotović, G.. (2024). Influence of Thickness Ratio on the Aerodynamic Characteristics of a Family of Hybrid Semielliptical Dolphin Airfoils. 
Springer Nature Switzerland AG..
https://doi.org/10.1007/978-3-031-42041-2_1

Dančuo Z, Kostić I, Kostić O, Bengin A, Vorotović G. Influence of Thickness Ratio on the Aerodynamic Characteristics of a Family of Hybrid Semielliptical Dolphin Airfoils. 2024;.
doi:10.1007/978-3-031-42041-2_1 .

Dančuo, Zorana, Kostić, Ivan, Kostić, Olivera, Bengin, Aleksandar, Vorotović, Goran, "Influence of Thickness Ratio on the Aerodynamic Characteristics of a Family of Hybrid Semielliptical Dolphin Airfoils" (2024),
https://doi.org/10.1007/978-3-031-42041-2_1 . .

TY  - JOUR
AU  - Kostić, Ivan
AU  - Tanović, Dragoljub
AU  - Kostić, Olivera
AU  - Abubaker, Ahmed Ali Irhayim
AU  - Simonović, Aleksandar
PY  - 2023
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/7713
AB  - Purpose: Unmanned aerial vehicles (UAV) with remote and/or automated flight and mission controls have replaced airplanes with pilots in many important roles. This study aims to deal with computational fluid dynamics (CFD) analysis and development of the aerodynamic configuration of a multi-purpose UAV for low and medium altitudes. The main aerodynamic requirement was the application of the tandem wing (TW) concept, where both wings generate a positive lift and act as primary lifting devices. Design/methodology/approach: Initial design analyses of the UAV’s aerodynamic configuration were performed using ANSYS Fluent. In previous work in Fluent, the authors established a calculation model that has been verified by experiments and, with minor adjustments, could be applied for subsonic, transonic and supersonic flow analyses. Findings: The design evolved through eight development configurations, where the latest V8 satisfied all the posted longitudinal aerodynamic requirements. Both wings generate a substantial amount of positive lift, whereas the initial stall occurs first on the front wing, generating a natural nose-down stall recovery tendency. In the cruising flight regime, this configuration has the desired range of longitudinal static stability and its centre of pressure is in close proximity to the centre of gravity. Practical implications: The intermediate development version V8 with proper longitudinal aerodynamic characteristics presents a good starting point for future development steps that will involve the optimization of lateral-directional aerodynamics. Originality/value: Using contemporary CFD tools, a novel and original TW aerodynamic configuration have evolved within eight development stages, not being based on or derived from any existing designs.
PB  - Emerald Publishing
T2  - Aircraft Engineering and Aerospace Technology
T1  - Initial development of tandem wing UAV aerodynamic configuration
EP  - 441
IS  - 3
SP  - 431
VL  - 95
DO  - 10.1108/AEAT-06-2022-0149
ER  - 

@article{
author = "Kostić, Ivan and Tanović, Dragoljub and Kostić, Olivera and Abubaker, Ahmed Ali Irhayim and Simonović, Aleksandar",
year = "2023",
abstract = "Purpose: Unmanned aerial vehicles (UAV) with remote and/or automated flight and mission controls have replaced airplanes with pilots in many important roles. This study aims to deal with computational fluid dynamics (CFD) analysis and development of the aerodynamic configuration of a multi-purpose UAV for low and medium altitudes. The main aerodynamic requirement was the application of the tandem wing (TW) concept, where both wings generate a positive lift and act as primary lifting devices. Design/methodology/approach: Initial design analyses of the UAV’s aerodynamic configuration were performed using ANSYS Fluent. In previous work in Fluent, the authors established a calculation model that has been verified by experiments and, with minor adjustments, could be applied for subsonic, transonic and supersonic flow analyses. Findings: The design evolved through eight development configurations, where the latest V8 satisfied all the posted longitudinal aerodynamic requirements. Both wings generate a substantial amount of positive lift, whereas the initial stall occurs first on the front wing, generating a natural nose-down stall recovery tendency. In the cruising flight regime, this configuration has the desired range of longitudinal static stability and its centre of pressure is in close proximity to the centre of gravity. Practical implications: The intermediate development version V8 with proper longitudinal aerodynamic characteristics presents a good starting point for future development steps that will involve the optimization of lateral-directional aerodynamics. Originality/value: Using contemporary CFD tools, a novel and original TW aerodynamic configuration have evolved within eight development stages, not being based on or derived from any existing designs.",
publisher = "Emerald Publishing",
journal = "Aircraft Engineering and Aerospace Technology",
title = "Initial development of tandem wing UAV aerodynamic configuration",
pages = "441-431",
number = "3",
volume = "95",
doi = "10.1108/AEAT-06-2022-0149"
}

Kostić, I., Tanović, D., Kostić, O., Abubaker, A. A. I.,& Simonović, A.. (2023). Initial development of tandem wing UAV aerodynamic configuration. in Aircraft Engineering and Aerospace Technology
Emerald Publishing., 95(3), 431-441.
https://doi.org/10.1108/AEAT-06-2022-0149

Kostić I, Tanović D, Kostić O, Abubaker AAI, Simonović A. Initial development of tandem wing UAV aerodynamic configuration. in Aircraft Engineering and Aerospace Technology. 2023;95(3):431-441.
doi:10.1108/AEAT-06-2022-0149 .

Kostić, Ivan, Tanović, Dragoljub, Kostić, Olivera, Abubaker, Ahmed Ali Irhayim, Simonović, Aleksandar, "Initial development of tandem wing UAV aerodynamic configuration" in Aircraft Engineering and Aerospace Technology, 95, no. 3 (2023):431-441,
https://doi.org/10.1108/AEAT-06-2022-0149 . .

Karakoc, H., Kostić, I., Grbović, A., Svorcan, J., Dalkiran, A., Ercan, A. H.,& Peković, O.. (2023). Novel Techniques in Maintenance, Repair, and Overhaul. in Proceedings of the International Symposium on Aviation Technology, MRO, and Operations 2022
Springer, Cham...
https://doi.org/10.1007/978-3-031-42041-2

Karakoc H, Kostić I, Grbović A, Svorcan J, Dalkiran A, Ercan AH, Peković O. Novel Techniques in Maintenance, Repair, and Overhaul. in Proceedings of the International Symposium on Aviation Technology, MRO, and Operations 2022. 2023;.
doi:10.1007/978-3-031-42041-2 .

Karakoc, Hikmet, Kostić, Ivan, Grbović, Aleksandar, Svorcan, Jelena, Dalkiran, Alper, Ercan, Ali Haydar, Peković, Ognjen, "Novel Techniques in Maintenance, Repair, and Overhaul" in Proceedings of the International Symposium on Aviation Technology, MRO, and Operations 2022 (2023),
https://doi.org/10.1007/978-3-031-42041-2 . .

TY  - JOUR
AU  - Dančuo, Zorana
AU  - Kostić, Ivan
AU  - Kostić, Olivera
AU  - Bengin, Aleksandar
AU  - Vorotović, Goran
PY  - 2022
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/3712
AB  - Iosif Taposu has formulated a mathematical model and generated a family of air-foils whose geometry resembles the dolphin shape. These airfoils are characterized by a sharp leading edge and experiments have proven that they can achieve better aerodynamic characteristics at very high angles of attack than certain classical airfoils, with the nose geometry inclined downwards. On the other hand, they have not been applied to any commercial general aviation aircraft. The authors of this paper have been motivated to compare the aerodynamic characteristics of widely used NACA 2415 airfoil with Taposu???s Dolphin that would have the same princi-pal geometric characteristics. A CFD calculation model has been established and applied on NACA 2415. The results were compared with NACA experiments and very good agreements have been achieved in the major domains of lift and polar curves. The same CFD model has been applied on the counterpart Dolphin 2415. Results have shown that the Dolphin has a slightly higher lift/drag ratio in the lift coefficient domain 0.1-0.35 than NACA. On the other hand, at higher and lower lift coefficients, its aerodynamic characteristics were drastically below those of the NACA section, due to the unfavorable influence of the Dolphin???s sharp nose. A series of the Dolphin???s leading edge modifications has been investigated, gradually improving its aerodynamics. Finally, version M4, consisting of about 70% of Dol-phin???s original rear domain and 30% of the new nose shape, managed to exceed the NACA???s characteristics, thus paving the way to investigate the Dolphin hybrids that could be suitable for the general aviation industry.
PB  - Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd
T2  - Thermal Science
T1  - Initial development of the hybrid semielliptical-dolphin airfoil
EP  - 2210
IS  - 3
SP  - 2199
VL  - 26
DO  - 10.2298/TSCI210515234D
ER  - 

@article{
author = "Dančuo, Zorana and Kostić, Ivan and Kostić, Olivera and Bengin, Aleksandar and Vorotović, Goran",
year = "2022",
abstract = "Iosif Taposu has formulated a mathematical model and generated a family of air-foils whose geometry resembles the dolphin shape. These airfoils are characterized by a sharp leading edge and experiments have proven that they can achieve better aerodynamic characteristics at very high angles of attack than certain classical airfoils, with the nose geometry inclined downwards. On the other hand, they have not been applied to any commercial general aviation aircraft. The authors of this paper have been motivated to compare the aerodynamic characteristics of widely used NACA 2415 airfoil with Taposu???s Dolphin that would have the same princi-pal geometric characteristics. A CFD calculation model has been established and applied on NACA 2415. The results were compared with NACA experiments and very good agreements have been achieved in the major domains of lift and polar curves. The same CFD model has been applied on the counterpart Dolphin 2415. Results have shown that the Dolphin has a slightly higher lift/drag ratio in the lift coefficient domain 0.1-0.35 than NACA. On the other hand, at higher and lower lift coefficients, its aerodynamic characteristics were drastically below those of the NACA section, due to the unfavorable influence of the Dolphin???s sharp nose. A series of the Dolphin???s leading edge modifications has been investigated, gradually improving its aerodynamics. Finally, version M4, consisting of about 70% of Dol-phin???s original rear domain and 30% of the new nose shape, managed to exceed the NACA???s characteristics, thus paving the way to investigate the Dolphin hybrids that could be suitable for the general aviation industry.",
publisher = "Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd",
journal = "Thermal Science",
title = "Initial development of the hybrid semielliptical-dolphin airfoil",
pages = "2210-2199",
number = "3",
volume = "26",
doi = "10.2298/TSCI210515234D"
}

Dančuo, Z., Kostić, I., Kostić, O., Bengin, A.,& Vorotović, G.. (2022). Initial development of the hybrid semielliptical-dolphin airfoil. in Thermal Science
Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd., 26(3), 2199-2210.
https://doi.org/10.2298/TSCI210515234D

Dančuo Z, Kostić I, Kostić O, Bengin A, Vorotović G. Initial development of the hybrid semielliptical-dolphin airfoil. in Thermal Science. 2022;26(3):2199-2210.
doi:10.2298/TSCI210515234D .

Dančuo, Zorana, Kostić, Ivan, Kostić, Olivera, Bengin, Aleksandar, Vorotović, Goran, "Initial development of the hybrid semielliptical-dolphin airfoil" in Thermal Science, 26, no. 3 (2022):2199-2210,
https://doi.org/10.2298/TSCI210515234D . .

TY  - JOUR
AU  - Popović, Lazar S.
AU  - Paunović, Lazar D.
AU  - Đilas, Veljko S.
AU  - Milutinović, Aleksandar M.
AU  - Ivanov, Toni
AU  - Kostić, Ivan
PY  - 2020
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/3362
AB  - Ovaj rad prezentuje metodologiju aerodinamičke optimizacije bespilotne letelice sa VTOL sposobnostima. Letelice kao što su ove obično lete pri malim brzinama, i zbog toga se očekuju mali Rejnoldsovi brojevi. Otpor trenja značajno zavisi od kvaliteta proizvodnog procesa. Prema tome, ukoliko se adekvatni koraci ne preduzmu, javiće se visoki koeficijenti trenja koji mogu drastično da promene performanse letelice. Promene geometrijskih parametara ne utiču samo na indukovani otpor krila, zbog osetljivosti na promene Rejnoldsovog broja utiču i na raspodelu profilnog otpora. Napisan je kod za proračun aerodinamičkih karakteristika krila zarad određivanja optimalnih geometrijskih parametara. Svi neophodni koeficijenti su izračunati korišćenjem Galuertovog rešenja Prantlove jednačine primenjenim na višesegmentna krila. Implementacijom aerodinamičkih koeficijenata brojnih eksperimentalno ispitanih aeroprofila optimizovanim za male Rejnoldsove brojeve, raspodela profilnog otpora, i indukovani otpor krila za veliki broj napadnih uglova su izračunati. Dobijeni rezultati su predstavljeni dijagramima, a metodologija za izbor najefikasnijeg krila je opisana. Dizajn T-oblika repnih površina je izvršen analitičkom metodom, dok su metoda vrtložne mreže, DATCOM, i CFD korišćeni za potrebe verifikacije rezultata.
AB  - This paper presents a methodology for aerodynamic optimization of UAV with VTOL capabilities. Aircrafts such as these usually fly at low speeds and due to that low Reynolds numbers are to be expected. The friction drag is highly dependent on the quality of the production process so unless special measures are undertaken, high friction drag coefficients could drastically influence overall performance of the aircraft. Changes of the geometrical parameters influence not only the induced drag of the wing, but also the distribution of the base drag due to sensitivity to changes of the Reynolds numbers. In order to determine the optimal geometrical parameters of the wing, a code for wing performance analysis was written. All necessary factors were calculated by utilizing the Glauert's solution of the Prandtl's equation for multi-segmented wings. By including experimental data of numerous airfoils optimized for low Reynolds numbers, the base drag distribution, along with the induced drag of the wings were calculated for a wide range of angles-of-attack. The obtained results are presented through diagrams and the methodology for the selection of the highest efficiency wing is described. The design of the T - shaped stabilizer was achieved by utilizing analytical methods while the Vortex Lattice Method, DATCOM and CFD were used for verification purposes.
PB  - Vojnotehnički institut, Beograd
T2  - Scientific Technical Review
T1  - Aerodinamički dizajn bespilotne letelice u više faza
T1  - Design of the UAV aerodynamics in multiple stages
EP  - 16
IS  - 2
SP  - 9
VL  - 70
DO  - 10.5937/str2002009P
ER  - 

@article{
author = "Popović, Lazar S. and Paunović, Lazar D. and Đilas, Veljko S. and Milutinović, Aleksandar M. and Ivanov, Toni and Kostić, Ivan",
year = "2020",
abstract = "Ovaj rad prezentuje metodologiju aerodinamičke optimizacije bespilotne letelice sa VTOL sposobnostima. Letelice kao što su ove obično lete pri malim brzinama, i zbog toga se očekuju mali Rejnoldsovi brojevi. Otpor trenja značajno zavisi od kvaliteta proizvodnog procesa. Prema tome, ukoliko se adekvatni koraci ne preduzmu, javiće se visoki koeficijenti trenja koji mogu drastično da promene performanse letelice. Promene geometrijskih parametara ne utiču samo na indukovani otpor krila, zbog osetljivosti na promene Rejnoldsovog broja utiču i na raspodelu profilnog otpora. Napisan je kod za proračun aerodinamičkih karakteristika krila zarad određivanja optimalnih geometrijskih parametara. Svi neophodni koeficijenti su izračunati korišćenjem Galuertovog rešenja Prantlove jednačine primenjenim na višesegmentna krila. Implementacijom aerodinamičkih koeficijenata brojnih eksperimentalno ispitanih aeroprofila optimizovanim za male Rejnoldsove brojeve, raspodela profilnog otpora, i indukovani otpor krila za veliki broj napadnih uglova su izračunati. Dobijeni rezultati su predstavljeni dijagramima, a metodologija za izbor najefikasnijeg krila je opisana. Dizajn T-oblika repnih površina je izvršen analitičkom metodom, dok su metoda vrtložne mreže, DATCOM, i CFD korišćeni za potrebe verifikacije rezultata., This paper presents a methodology for aerodynamic optimization of UAV with VTOL capabilities. Aircrafts such as these usually fly at low speeds and due to that low Reynolds numbers are to be expected. The friction drag is highly dependent on the quality of the production process so unless special measures are undertaken, high friction drag coefficients could drastically influence overall performance of the aircraft. Changes of the geometrical parameters influence not only the induced drag of the wing, but also the distribution of the base drag due to sensitivity to changes of the Reynolds numbers. In order to determine the optimal geometrical parameters of the wing, a code for wing performance analysis was written. All necessary factors were calculated by utilizing the Glauert's solution of the Prandtl's equation for multi-segmented wings. By including experimental data of numerous airfoils optimized for low Reynolds numbers, the base drag distribution, along with the induced drag of the wings were calculated for a wide range of angles-of-attack. The obtained results are presented through diagrams and the methodology for the selection of the highest efficiency wing is described. The design of the T - shaped stabilizer was achieved by utilizing analytical methods while the Vortex Lattice Method, DATCOM and CFD were used for verification purposes.",
publisher = "Vojnotehnički institut, Beograd",
journal = "Scientific Technical Review",
title = "Aerodinamički dizajn bespilotne letelice u više faza, Design of the UAV aerodynamics in multiple stages",
pages = "16-9",
number = "2",
volume = "70",
doi = "10.5937/str2002009P"
}

Popović, L. S., Paunović, L. D., Đilas, V. S., Milutinović, A. M., Ivanov, T.,& Kostić, I.. (2020). Aerodinamički dizajn bespilotne letelice u više faza. in Scientific Technical Review
Vojnotehnički institut, Beograd., 70(2), 9-16.
https://doi.org/10.5937/str2002009P

Popović LS, Paunović LD, Đilas VS, Milutinović AM, Ivanov T, Kostić I. Aerodinamički dizajn bespilotne letelice u više faza. in Scientific Technical Review. 2020;70(2):9-16.
doi:10.5937/str2002009P .

Popović, Lazar S., Paunović, Lazar D., Đilas, Veljko S., Milutinović, Aleksandar M., Ivanov, Toni, Kostić, Ivan, "Aerodinamički dizajn bespilotne letelice u više faza" in Scientific Technical Review, 70, no. 2 (2020):9-16,
https://doi.org/10.5937/str2002009P . .

TY  - CONF
AU  - Hasan, Mohammad Sakib
AU  - Svorcan, Jelena
AU  - Kostić, Ivan
AU  - Simonović, Aleksandar
AU  - Kostić, Srđan
AU  - Ivanov, Toni
PY  - 2018
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/4303
AB  - Observation, maintenance, surveillance, monitoring, remote sensing and security tasks could be defined as the main application of UAVs (Unmanned Air Vehicle). In spite of the fact that all UAV systems have many elements other than the air vehicle, they are frequently classified by the capability or size of the UAVs that is required to perform the mission. Air forces are using HALE (High Altitude Long Endurance) UAVs from fixed bases which can carry out extremely long-range
reconnaissance and surveillance. Different types of wing are used in unmanned air vehicle. This paper represents preliminary aerodynamic performance estimation of HALE UAV wings.
PB  - Belgrade :  Military Technical Institute - VTI
C3  - Proceedings / 8th International Scientific Conference on Defensive Technologies OTEH 2018
T1  - Preliminary aerodynamic performance estimation of HALE UAV wings
EP  - 43
SP  - 39
UR  - https://hdl.handle.net/21.15107/rcub_machinery_4303
ER  - 

@conference{
author = "Hasan, Mohammad Sakib and Svorcan, Jelena and Kostić, Ivan and Simonović, Aleksandar and Kostić, Srđan and Ivanov, Toni",
year = "2018",
abstract = "Observation, maintenance, surveillance, monitoring, remote sensing and security tasks could be defined as the main application of UAVs (Unmanned Air Vehicle). In spite of the fact that all UAV systems have many elements other than the air vehicle, they are frequently classified by the capability or size of the UAVs that is required to perform the mission. Air forces are using HALE (High Altitude Long Endurance) UAVs from fixed bases which can carry out extremely long-range
reconnaissance and surveillance. Different types of wing are used in unmanned air vehicle. This paper represents preliminary aerodynamic performance estimation of HALE UAV wings.",
publisher = "Belgrade :  Military Technical Institute - VTI",
journal = "Proceedings / 8th International Scientific Conference on Defensive Technologies OTEH 2018",
title = "Preliminary aerodynamic performance estimation of HALE UAV wings",
pages = "43-39",
url = "https://hdl.handle.net/21.15107/rcub_machinery_4303"
}

Hasan, M. S., Svorcan, J., Kostić, I., Simonović, A., Kostić, S.,& Ivanov, T.. (2018). Preliminary aerodynamic performance estimation of HALE UAV wings. in Proceedings / 8th International Scientific Conference on Defensive Technologies OTEH 2018
Belgrade :  Military Technical Institute - VTI., 39-43.
https://hdl.handle.net/21.15107/rcub_machinery_4303

Hasan MS, Svorcan J, Kostić I, Simonović A, Kostić S, Ivanov T. Preliminary aerodynamic performance estimation of HALE UAV wings. in Proceedings / 8th International Scientific Conference on Defensive Technologies OTEH 2018. 2018;:39-43.
https://hdl.handle.net/21.15107/rcub_machinery_4303 .

Hasan, Mohammad Sakib, Svorcan, Jelena, Kostić, Ivan, Simonović, Aleksandar, Kostić, Srđan, Ivanov, Toni, "Preliminary aerodynamic performance estimation of HALE UAV wings" in Proceedings / 8th International Scientific Conference on Defensive Technologies OTEH 2018 (2018):39-43,
https://hdl.handle.net/21.15107/rcub_machinery_4303 .

TY  - CONF
AU  - Abubaker, A.
AU  - Kostić, Ivan
AU  - Kostić, Olivera
PY  - 2018
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2976
AB  - Experimental and numerical modeling and simulations of the wind influence within the atmospheric boundary layer are essential tools in optimum building structural design. Each of these methods, however, has both advantages and disadvantages. In experimental investigations performed in wind tunnels, reliable results can be obtained, but detailed information of the wind profile parameters, such as the surface roughness length z 0 or the friction velocity u∗, are difficult to determine. Numerical simulations, on other hand, easily yield any information of the wind velocity profile. However, the reliability of numerical results strongly depends on the established and adopted computational model. This paper presents the computational fluid dynamics (CFD) analysis of the atmospheric boundary layer simulated in subsonic wind tunnels using appropriate types of obstacles, based on the SST k-ω turbulence model with optimized unstructured mesh and optimum selection of relevant physical model parameters, performed in Ansys Fluent software. Results have been compared with the measurements from the Assiut University wind tunnel with maximum velocity of 4 m/s, and from subsonic wind tunnel at Belgrade University, with maximum air velocity of 45 m/s. Detailed comparisons for velocity distributions with these experimental results have shown very good conformity. Also, the three-parameter fitting methods were successfully established to define surface roughness length z 0 and the friction velocity u∗. Obtained results have shown that the established numerical model is able to substitute a remarkable number of expensive wind tunnel tests hours within the operational investigations of wind influence on the building structures.
PB  - Institute of Physics Publishing
C3  - IOP Conference Series: Materials Science and Engineering
T1  - Numerical modelling of velocity profile parameters of the atmospheric boundary layer simulated in wind tunnels
IS  - 1
VL  - 393
DO  - 10.1088/1757-899X/393/1/012025
ER  - 

@conference{
author = "Abubaker, A. and Kostić, Ivan and Kostić, Olivera",
year = "2018",
abstract = "Experimental and numerical modeling and simulations of the wind influence within the atmospheric boundary layer are essential tools in optimum building structural design. Each of these methods, however, has both advantages and disadvantages. In experimental investigations performed in wind tunnels, reliable results can be obtained, but detailed information of the wind profile parameters, such as the surface roughness length z 0 or the friction velocity u∗, are difficult to determine. Numerical simulations, on other hand, easily yield any information of the wind velocity profile. However, the reliability of numerical results strongly depends on the established and adopted computational model. This paper presents the computational fluid dynamics (CFD) analysis of the atmospheric boundary layer simulated in subsonic wind tunnels using appropriate types of obstacles, based on the SST k-ω turbulence model with optimized unstructured mesh and optimum selection of relevant physical model parameters, performed in Ansys Fluent software. Results have been compared with the measurements from the Assiut University wind tunnel with maximum velocity of 4 m/s, and from subsonic wind tunnel at Belgrade University, with maximum air velocity of 45 m/s. Detailed comparisons for velocity distributions with these experimental results have shown very good conformity. Also, the three-parameter fitting methods were successfully established to define surface roughness length z 0 and the friction velocity u∗. Obtained results have shown that the established numerical model is able to substitute a remarkable number of expensive wind tunnel tests hours within the operational investigations of wind influence on the building structures.",
publisher = "Institute of Physics Publishing",
journal = "IOP Conference Series: Materials Science and Engineering",
title = "Numerical modelling of velocity profile parameters of the atmospheric boundary layer simulated in wind tunnels",
number = "1",
volume = "393",
doi = "10.1088/1757-899X/393/1/012025"
}

Abubaker, A., Kostić, I.,& Kostić, O.. (2018). Numerical modelling of velocity profile parameters of the atmospheric boundary layer simulated in wind tunnels. in IOP Conference Series: Materials Science and Engineering
Institute of Physics Publishing., 393(1).
https://doi.org/10.1088/1757-899X/393/1/012025

Abubaker A, Kostić I, Kostić O. Numerical modelling of velocity profile parameters of the atmospheric boundary layer simulated in wind tunnels. in IOP Conference Series: Materials Science and Engineering. 2018;393(1).
doi:10.1088/1757-899X/393/1/012025 .

Abubaker, A., Kostić, Ivan, Kostić, Olivera, "Numerical modelling of velocity profile parameters of the atmospheric boundary layer simulated in wind tunnels" in IOP Conference Series: Materials Science and Engineering, 393, no. 1 (2018),
https://doi.org/10.1088/1757-899X/393/1/012025 . .

TY  - JOUR
AU  - Abubaker, Ahmed
AU  - Kostić, Ivan
AU  - Kostić, Olivera
AU  - Stefanović, Zoran
PY  - 2018
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2890
AB  - Wind tunnel tests of wind influence on ground objects require proper experimental modeling of the atmospheric boundary layer (ABL). The authors have performed computational analyses with an aim to establish a reliable computational algorithm that could resemble complex flow patterns in wind tunnels with various obstacles, used to simulate appropriate velocity profiles within the ABL. For experimental verifications, measurements from two experimental facilities were applied, with speeds ranging from 1-4 m/s in the first, and 45 m/s in the second. For all considered cases, good agreements between the measured and computed speed profiles for operational engineering purposes have been achieved. In the sense of qualitative analyses, calculated contours of velocity magnitude and eddy viscosity inside the wind tunnel test sections have verified that good homogeneity of the simulated ABL in both wind tunnels had been established in the domains where velocity profiles were measured. Presented results have shown the capability of here established calculation model to resemble a number of costly wind tunnel test hours during preparations of proper obstacle arrangements for experimental ABL modeling in a wide wind speed range, and thus reduce the overall project costs. Also, presented CFD algorithm can readily be calibrated and used for engineering research of wind effects on different ground objects, as a virtual wind tunnel.
PB  - Univ Osijek, Tech Fac, Slavonski Brod
T2  - Tehnički vjesnik
T1  - CFD Modeling of Atmospheric Boundary Layer Simulations in Wind Tunnels
EP  - 1602
IS  - 6
SP  - 1595
VL  - 25
DO  - 10.17559/TV-20161125134410
ER  - 

@article{
author = "Abubaker, Ahmed and Kostić, Ivan and Kostić, Olivera and Stefanović, Zoran",
year = "2018",
abstract = "Wind tunnel tests of wind influence on ground objects require proper experimental modeling of the atmospheric boundary layer (ABL). The authors have performed computational analyses with an aim to establish a reliable computational algorithm that could resemble complex flow patterns in wind tunnels with various obstacles, used to simulate appropriate velocity profiles within the ABL. For experimental verifications, measurements from two experimental facilities were applied, with speeds ranging from 1-4 m/s in the first, and 45 m/s in the second. For all considered cases, good agreements between the measured and computed speed profiles for operational engineering purposes have been achieved. In the sense of qualitative analyses, calculated contours of velocity magnitude and eddy viscosity inside the wind tunnel test sections have verified that good homogeneity of the simulated ABL in both wind tunnels had been established in the domains where velocity profiles were measured. Presented results have shown the capability of here established calculation model to resemble a number of costly wind tunnel test hours during preparations of proper obstacle arrangements for experimental ABL modeling in a wide wind speed range, and thus reduce the overall project costs. Also, presented CFD algorithm can readily be calibrated and used for engineering research of wind effects on different ground objects, as a virtual wind tunnel.",
publisher = "Univ Osijek, Tech Fac, Slavonski Brod",
journal = "Tehnički vjesnik",
title = "CFD Modeling of Atmospheric Boundary Layer Simulations in Wind Tunnels",
pages = "1602-1595",
number = "6",
volume = "25",
doi = "10.17559/TV-20161125134410"
}

Abubaker, A., Kostić, I., Kostić, O.,& Stefanović, Z.. (2018). CFD Modeling of Atmospheric Boundary Layer Simulations in Wind Tunnels. in Tehnički vjesnik
Univ Osijek, Tech Fac, Slavonski Brod., 25(6), 1595-1602.
https://doi.org/10.17559/TV-20161125134410

Abubaker A, Kostić I, Kostić O, Stefanović Z. CFD Modeling of Atmospheric Boundary Layer Simulations in Wind Tunnels. in Tehnički vjesnik. 2018;25(6):1595-1602.
doi:10.17559/TV-20161125134410 .

Abubaker, Ahmed, Kostić, Ivan, Kostić, Olivera, Stefanović, Zoran, "CFD Modeling of Atmospheric Boundary Layer Simulations in Wind Tunnels" in Tehnički vjesnik, 25, no. 6 (2018):1595-1602,
https://doi.org/10.17559/TV-20161125134410 . .

TY  - JOUR
AU  - Kostić, Olivera
AU  - Stefanović, Zoran
AU  - Kostić, Ivan
PY  - 2017
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2579
AB  - In this study, a CFD (Computational Fluid Dynamics) computational model has been established, with the aim to properly simulate complex supersonic flow generated by a 2D convergent-divergent nozzle. For the purpose of rocket engine thrust vector control (TVC) simulations, initially several jet tab positions were used to generate up to 30% shadowing of the nozzle exit, without and with a gap between tab and exit. Numerical results were compared with the existing experimental data, both quantitatively and qualitatively, and fair agreements have been obtained in both senses. The same CFD settings have then been applied for the computational analysis of another TVC type - the jet vane, which was analysed in four different adopted configurations with respect to the nozzle. Stable convergence of solutions has been achieved, up to 40 degrees of vane deflections. Performed calculations have enabled comparisons of the two considered TVC types, in the sense of the achieved thrust force deflections, and thrust losses.
PB  - Univ Osijek, Tech Fac, Slavonski Brod
T2  - Tehnički vjesnik
T1  - Comparative cfd analyses of a 2d supersonic nozzle flow with jet tab and jet vane
EP  - 1344
IS  - 5
SP  - 1335
VL  - 24
DO  - 10.17559/TV-20160208145336
ER  - 

@article{
author = "Kostić, Olivera and Stefanović, Zoran and Kostić, Ivan",
year = "2017",
abstract = "In this study, a CFD (Computational Fluid Dynamics) computational model has been established, with the aim to properly simulate complex supersonic flow generated by a 2D convergent-divergent nozzle. For the purpose of rocket engine thrust vector control (TVC) simulations, initially several jet tab positions were used to generate up to 30% shadowing of the nozzle exit, without and with a gap between tab and exit. Numerical results were compared with the existing experimental data, both quantitatively and qualitatively, and fair agreements have been obtained in both senses. The same CFD settings have then been applied for the computational analysis of another TVC type - the jet vane, which was analysed in four different adopted configurations with respect to the nozzle. Stable convergence of solutions has been achieved, up to 40 degrees of vane deflections. Performed calculations have enabled comparisons of the two considered TVC types, in the sense of the achieved thrust force deflections, and thrust losses.",
publisher = "Univ Osijek, Tech Fac, Slavonski Brod",
journal = "Tehnički vjesnik",
title = "Comparative cfd analyses of a 2d supersonic nozzle flow with jet tab and jet vane",
pages = "1344-1335",
number = "5",
volume = "24",
doi = "10.17559/TV-20160208145336"
}

Kostić, O., Stefanović, Z.,& Kostić, I.. (2017). Comparative cfd analyses of a 2d supersonic nozzle flow with jet tab and jet vane. in Tehnički vjesnik
Univ Osijek, Tech Fac, Slavonski Brod., 24(5), 1335-1344.
https://doi.org/10.17559/TV-20160208145336

Kostić O, Stefanović Z, Kostić I. Comparative cfd analyses of a 2d supersonic nozzle flow with jet tab and jet vane. in Tehnički vjesnik. 2017;24(5):1335-1344.
doi:10.17559/TV-20160208145336 .

Kostić, Olivera, Stefanović, Zoran, Kostić, Ivan, "Comparative cfd analyses of a 2d supersonic nozzle flow with jet tab and jet vane" in Tehnički vjesnik, 24, no. 5 (2017):1335-1344,
https://doi.org/10.17559/TV-20160208145336 . .

TY  - JOUR
AU  - Ivanov, Toni
AU  - Simonović, Aleksandar
AU  - Petrović, Nebojša
AU  - Fotev, Vasko
AU  - Kostić, Ivan
PY  - 2017
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2654
AB  - An airfoil was parameterized using the class-shape transformation technique and then optimized via genetic algorithm. The aerodynamic characteristics of the airfoil were obtained with the use of a CFD software. The automated numerical technique was validated using available experimental data and then the optimization procedure was repeated for few different turbulence models. The obtained optimized airfoils were then compared in order to gain some insight on the influence of the different turbulence models on the optimization result.
PB  - Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd
T2  - Thermal Science
T1  - Influence of selected turbulence model on the optimization of a class-shape transformation parameterized airfoil
EP  - S744
SP  - S737
VL  - 21
DO  - 10.2298/TSCI160209194I
ER  - 

@article{
author = "Ivanov, Toni and Simonović, Aleksandar and Petrović, Nebojša and Fotev, Vasko and Kostić, Ivan",
year = "2017",
abstract = "An airfoil was parameterized using the class-shape transformation technique and then optimized via genetic algorithm. The aerodynamic characteristics of the airfoil were obtained with the use of a CFD software. The automated numerical technique was validated using available experimental data and then the optimization procedure was repeated for few different turbulence models. The obtained optimized airfoils were then compared in order to gain some insight on the influence of the different turbulence models on the optimization result.",
publisher = "Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd",
journal = "Thermal Science",
title = "Influence of selected turbulence model on the optimization of a class-shape transformation parameterized airfoil",
pages = "S744-S737",
volume = "21",
doi = "10.2298/TSCI160209194I"
}

Ivanov, T., Simonović, A., Petrović, N., Fotev, V.,& Kostić, I.. (2017). Influence of selected turbulence model on the optimization of a class-shape transformation parameterized airfoil. in Thermal Science
Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd., 21, S737-S744.
https://doi.org/10.2298/TSCI160209194I

Ivanov T, Simonović A, Petrović N, Fotev V, Kostić I. Influence of selected turbulence model on the optimization of a class-shape transformation parameterized airfoil. in Thermal Science. 2017;21:S737-S744.
doi:10.2298/TSCI160209194I .

Ivanov, Toni, Simonović, Aleksandar, Petrović, Nebojša, Fotev, Vasko, Kostić, Ivan, "Influence of selected turbulence model on the optimization of a class-shape transformation parameterized airfoil" in Thermal Science, 21 (2017):S737-S744,
https://doi.org/10.2298/TSCI160209194I . .

TY  - JOUR
AU  - Sekutkovski, Bojan
AU  - Kostić, Ivan
AU  - Simonović, Aleksandar
AU  - Cardiff, Philip
AU  - Jazarević, Vladimir
PY  - 2016
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2465
AB  - Current industrial practice for the fluid-structure interaction (FSI) analyses and prediction of aeroelastic phenomena, such as flutter, is heavily based on linear methods. These methods involve many of design limitations and envelope restrictions for aircraft. In this paper novel hybrid Reynolds-Averaged Navier-Stokes - Large Eddy Simulation (RANS-LES) turbulence model, i.e. k-Omega Shear Stress Transport Scale-Adaptive Improved Delayed Detached Eddy Simulation (k-Omega SST SA IDDES) is tested and implemented in the FSI procedure and is applied in transonic flow. This model is also compared with the lower fidelity RANS models, i.e. k-omega SST and Spalart-Allmaras. More precisely, a strongly coupled three-dimensional (3D) PSI solver is combined with the turbulence model and large deformation updated Lagrangian finite volume structural solver in order to resolve standard computational fluid dynamics (CFD) and aeroelastic benchmark cases of transonic flow. The turbulence model combines the advanced capabilities of the existing SST, SAS and IDDES turbulence models. Unsteadiness detection deficiency of SAS is automatically supplemented by the IDDES term included in kinetic energy equation. The numerical results of Onera M6 and AGARD 445.6 validation cases are presented and compared with the existing experimental results. Discretization of the governing equations is performed by cell-centered finite volume method (FVM) on unstructured meshes. Further application of the FSI procedure for the FSI analyzes of the whole aircraft structures is one of the aims. The emphasis is made on turbulence modeling which appears to have a major impact to the prediction of FSI behavior in transonic flow domain. In this work the aeroelasticity is treated as one of the many FSI branches. Described FSI solver is custom written and implemented in OpenFOAM.
PB  - Elsevier France-Editions Scientifiques Medicales Elsevier, Issy-Les-Moulineaux
T2  - Aerospace Science and Technology
T1  - Three-dimensional fluid-structure interaction simulation with a hybrid RANS-LES turbulence model for applications in transonic flow domain
EP  - 16
SP  - 1
VL  - 49
DO  - 10.1016/j.ast.2015.11.028
ER  - 

@article{
author = "Sekutkovski, Bojan and Kostić, Ivan and Simonović, Aleksandar and Cardiff, Philip and Jazarević, Vladimir",
year = "2016",
abstract = "Current industrial practice for the fluid-structure interaction (FSI) analyses and prediction of aeroelastic phenomena, such as flutter, is heavily based on linear methods. These methods involve many of design limitations and envelope restrictions for aircraft. In this paper novel hybrid Reynolds-Averaged Navier-Stokes - Large Eddy Simulation (RANS-LES) turbulence model, i.e. k-Omega Shear Stress Transport Scale-Adaptive Improved Delayed Detached Eddy Simulation (k-Omega SST SA IDDES) is tested and implemented in the FSI procedure and is applied in transonic flow. This model is also compared with the lower fidelity RANS models, i.e. k-omega SST and Spalart-Allmaras. More precisely, a strongly coupled three-dimensional (3D) PSI solver is combined with the turbulence model and large deformation updated Lagrangian finite volume structural solver in order to resolve standard computational fluid dynamics (CFD) and aeroelastic benchmark cases of transonic flow. The turbulence model combines the advanced capabilities of the existing SST, SAS and IDDES turbulence models. Unsteadiness detection deficiency of SAS is automatically supplemented by the IDDES term included in kinetic energy equation. The numerical results of Onera M6 and AGARD 445.6 validation cases are presented and compared with the existing experimental results. Discretization of the governing equations is performed by cell-centered finite volume method (FVM) on unstructured meshes. Further application of the FSI procedure for the FSI analyzes of the whole aircraft structures is one of the aims. The emphasis is made on turbulence modeling which appears to have a major impact to the prediction of FSI behavior in transonic flow domain. In this work the aeroelasticity is treated as one of the many FSI branches. Described FSI solver is custom written and implemented in OpenFOAM.",
publisher = "Elsevier France-Editions Scientifiques Medicales Elsevier, Issy-Les-Moulineaux",
journal = "Aerospace Science and Technology",
title = "Three-dimensional fluid-structure interaction simulation with a hybrid RANS-LES turbulence model for applications in transonic flow domain",
pages = "16-1",
volume = "49",
doi = "10.1016/j.ast.2015.11.028"
}

Sekutkovski, B., Kostić, I., Simonović, A., Cardiff, P.,& Jazarević, V.. (2016). Three-dimensional fluid-structure interaction simulation with a hybrid RANS-LES turbulence model for applications in transonic flow domain. in Aerospace Science and Technology
Elsevier France-Editions Scientifiques Medicales Elsevier, Issy-Les-Moulineaux., 49, 1-16.
https://doi.org/10.1016/j.ast.2015.11.028

Sekutkovski B, Kostić I, Simonović A, Cardiff P, Jazarević V. Three-dimensional fluid-structure interaction simulation with a hybrid RANS-LES turbulence model for applications in transonic flow domain. in Aerospace Science and Technology. 2016;49:1-16.
doi:10.1016/j.ast.2015.11.028 .

Sekutkovski, Bojan, Kostić, Ivan, Simonović, Aleksandar, Cardiff, Philip, Jazarević, Vladimir, "Three-dimensional fluid-structure interaction simulation with a hybrid RANS-LES turbulence model for applications in transonic flow domain" in Aerospace Science and Technology, 49 (2016):1-16,
https://doi.org/10.1016/j.ast.2015.11.028 . .

TY  - JOUR
AU  - Abdullah, Taha Ahmed
AU  - Petrović, Zlatko
AU  - Stefanović, Zoran
AU  - Kostić, Ivan
AU  - Isaković, Jovan
PY  - 2015
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2246
AB  - The correction method for pressure coefficient distribution around an airfoil is developed for the purpose of the postprocessing of wind tunnel data, obtained from the model pressure measurements. Pressure coefficient distribution around the airfoil, directly obtained by wind tunnel measurements, is corrected numerically in order to compensate for the interference effects of the wind tunnel test section walls. In this paper, the airfoil NACA0012 is approximated by linear vortex segments, which are then mirrored using sufficient number of images with respect to the ceiling and the floor of the test section, to model the flow pattern around an airfoil in the wind tunnel test section with solid walls. Flow calculations, both with the tunnel wall presence and in the free stream, are then performed. The numerically obtained pressure coefficient difference between these two cases should be superimposed to the pressure coefficient distribution measured in the wind tunnel, for the same nominal airflow parameters and angle of attack, at the corresponding points, resulting in the corrected experimental pressure coefficient distribution. The values of corrections generally increase with the reduction of the wind tunnel test section relative height. The paper is focused on the verification of lift curve slope corrections, where very good agreements have been obtained with several well-known classical correction methods.
PB  - Univ Osijek, Tech Fac, Slavonski Brod
T2  - Tehnički vjesnik
T1  - Two-dimensional wind tunnel measurement corrections by the singularity method
EP  - 565
IS  - 3
SP  - 557
VL  - 22
DO  - 10.17559/TV-20140214114718
ER  - 

@article{
author = "Abdullah, Taha Ahmed and Petrović, Zlatko and Stefanović, Zoran and Kostić, Ivan and Isaković, Jovan",
year = "2015",
abstract = "The correction method for pressure coefficient distribution around an airfoil is developed for the purpose of the postprocessing of wind tunnel data, obtained from the model pressure measurements. Pressure coefficient distribution around the airfoil, directly obtained by wind tunnel measurements, is corrected numerically in order to compensate for the interference effects of the wind tunnel test section walls. In this paper, the airfoil NACA0012 is approximated by linear vortex segments, which are then mirrored using sufficient number of images with respect to the ceiling and the floor of the test section, to model the flow pattern around an airfoil in the wind tunnel test section with solid walls. Flow calculations, both with the tunnel wall presence and in the free stream, are then performed. The numerically obtained pressure coefficient difference between these two cases should be superimposed to the pressure coefficient distribution measured in the wind tunnel, for the same nominal airflow parameters and angle of attack, at the corresponding points, resulting in the corrected experimental pressure coefficient distribution. The values of corrections generally increase with the reduction of the wind tunnel test section relative height. The paper is focused on the verification of lift curve slope corrections, where very good agreements have been obtained with several well-known classical correction methods.",
publisher = "Univ Osijek, Tech Fac, Slavonski Brod",
journal = "Tehnički vjesnik",
title = "Two-dimensional wind tunnel measurement corrections by the singularity method",
pages = "565-557",
number = "3",
volume = "22",
doi = "10.17559/TV-20140214114718"
}

Abdullah, T. A., Petrović, Z., Stefanović, Z., Kostić, I.,& Isaković, J.. (2015). Two-dimensional wind tunnel measurement corrections by the singularity method. in Tehnički vjesnik
Univ Osijek, Tech Fac, Slavonski Brod., 22(3), 557-565.
https://doi.org/10.17559/TV-20140214114718

Abdullah TA, Petrović Z, Stefanović Z, Kostić I, Isaković J. Two-dimensional wind tunnel measurement corrections by the singularity method. in Tehnički vjesnik. 2015;22(3):557-565.
doi:10.17559/TV-20140214114718 .

Abdullah, Taha Ahmed, Petrović, Zlatko, Stefanović, Zoran, Kostić, Ivan, Isaković, Jovan, "Two-dimensional wind tunnel measurement corrections by the singularity method" in Tehnički vjesnik, 22, no. 3 (2015):557-565,
https://doi.org/10.17559/TV-20140214114718 . .

TY  - JOUR
AU  - Sekutkovski, Bojan
AU  - Kostić, Ivan
AU  - Stefanović, Zoran
AU  - Simonović, Aleksandar
AU  - Kostić, Olivera
PY  - 2015
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2245
AB  - Three-dimensional, compressible, viscous and transient transonic turbulent flow over the wing was simulated by a hybrid RANS-LES modelling method, combined with the compressible k-omegaSSTSAS turbulence model. This approach is based on dividing the contribution of the fluctuating and the averaged velocity fields in the subgrid tensor, and modelling each of them with its corresponding turbulent viscosity. The "RANS mode" is used in flow field domains which can be treated with acceptable accuracy as relatively steady, such as in the boundary layer, while the "LES mode" is applied in the dominantly unsteady regions, far from the wing. Discretization of the governing equations is performed by Finite Volume Method on unstructured mesh. The method has been verified on the Onera M6 wing. The parallelization is achieved by decomposing the mesh into sub-domains and using the Open MPI technology. The implementation of turbulence model has been done using OpenFOAM. The flow simulation was also performed using ANSYS Fluent, and the results of the two methods were compared mutually, and with the Onera M6 experiment.
PB  - Univ Osijek, Tech Fac, Slavonski Brod
T2  - Tehnički vjesnik
T1  - A hybrid rans-les method with compressible k-omegasstsas turbulence model for high reynolds number flow applications
EP  - 1245
IS  - 5
SP  - 1237
VL  - 22
DO  - 10.17559/TV-20140404130058
ER  - 

@article{
author = "Sekutkovski, Bojan and Kostić, Ivan and Stefanović, Zoran and Simonović, Aleksandar and Kostić, Olivera",
year = "2015",
abstract = "Three-dimensional, compressible, viscous and transient transonic turbulent flow over the wing was simulated by a hybrid RANS-LES modelling method, combined with the compressible k-omegaSSTSAS turbulence model. This approach is based on dividing the contribution of the fluctuating and the averaged velocity fields in the subgrid tensor, and modelling each of them with its corresponding turbulent viscosity. The "RANS mode" is used in flow field domains which can be treated with acceptable accuracy as relatively steady, such as in the boundary layer, while the "LES mode" is applied in the dominantly unsteady regions, far from the wing. Discretization of the governing equations is performed by Finite Volume Method on unstructured mesh. The method has been verified on the Onera M6 wing. The parallelization is achieved by decomposing the mesh into sub-domains and using the Open MPI technology. The implementation of turbulence model has been done using OpenFOAM. The flow simulation was also performed using ANSYS Fluent, and the results of the two methods were compared mutually, and with the Onera M6 experiment.",
publisher = "Univ Osijek, Tech Fac, Slavonski Brod",
journal = "Tehnički vjesnik",
title = "A hybrid rans-les method with compressible k-omegasstsas turbulence model for high reynolds number flow applications",
pages = "1245-1237",
number = "5",
volume = "22",
doi = "10.17559/TV-20140404130058"
}

Sekutkovski, B., Kostić, I., Stefanović, Z., Simonović, A.,& Kostić, O.. (2015). A hybrid rans-les method with compressible k-omegasstsas turbulence model for high reynolds number flow applications. in Tehnički vjesnik
Univ Osijek, Tech Fac, Slavonski Brod., 22(5), 1237-1245.
https://doi.org/10.17559/TV-20140404130058

Sekutkovski B, Kostić I, Stefanović Z, Simonović A, Kostić O. A hybrid rans-les method with compressible k-omegasstsas turbulence model for high reynolds number flow applications. in Tehnički vjesnik. 2015;22(5):1237-1245.
doi:10.17559/TV-20140404130058 .

Sekutkovski, Bojan, Kostić, Ivan, Stefanović, Zoran, Simonović, Aleksandar, Kostić, Olivera, "A hybrid rans-les method with compressible k-omegasstsas turbulence model for high reynolds number flow applications" in Tehnički vjesnik, 22, no. 5 (2015):1237-1245,
https://doi.org/10.17559/TV-20140404130058 . .

TY  - JOUR
AU  - Kostić, Olivera
AU  - Stefanović, Zoran
AU  - Kostić, Ivan
PY  - 2015
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2149
AB  - Modeliranje složenih nadzvučnih strujnih polja korišćenjem računara predstavlja jedan od najvećih izazova u oblasti CFD analiza. U radu su predstavljeni prvi koraci u numeričkoj analizi takvog strujanja, generisanog konvergentno- divergentnim mlaznikom sa Mahovim brojem M = 2.6 na izlazu iz mlaznika. Cilj je bio postići dobra poklapanja sa raspoloživim eksperimentalnim podacima, dobijenim tokom ispitivanja u nadzvučnom aerotunelu instituta VTI Žarkovo, gde su ispitivane mogućnosti vektorisanja potiska mlaznika sa vazduhom kao radnim fluidom, postavljanjem različitih tipova prepreka na izlazu iza mlaznika. U radu se analiziraju slučajevi strujanja sa slobodnim izlazom i sa jednim izabranim tipom prepreke na izlazu iz mlaznika. Za oba slučaja korišćene su strukturirane proračunske mreže za rešavanje RANS jednačina sa k-w SST turbulentnim modelom. Nakon kvalitativnih i kvantitativnih poređenja sa raspoloživim eksperimentalnim rezultatima, utvrđena su dobra poklapanja, pri čemu je CFD analiza bila u mogućnosti da pruži i dodatne podatke o strujnom polju, koji nisu mereni tokom eksperimenata.
AB  - Computational modeling of complex supersonic airflow patterns is one of the greatest challenges in the domain of CFD analyses. The paper presents initial steps in numerical analysis of such flow, generated by convergentdivergent nozzle with Mach number M = 2.6 at nozzle exit. The aim was to achieve good agreements with available experimental data, obtained during supersonic wind tunnel tests at VTI Žarkovo institute, where nozzle thrust vectoring possibilities had been investigated using air as test fluid, by placing different types of obstacles at the exit section. Paper is focussed on free exit flow, and flow with one selected obstacle type. Using structured mesh for both cases, the RANS equations with k-w SST turbulent model have been applied. After quantitative and qualitative comparisons with available experimental data, good agreements have been obtained, where CFD was also able to provide additional flowfield data, not measuted during experiments.
PB  - Univerzitet u Beogradu - Mašinski fakultet, Beograd
T2  - FME Transactions
T1  - CFD modeliranje nadzvučne vazdušne struje generisane 2D mlaznikom sa preprekom i bez prepreke na izlazu
T1  - CFD modeling of supersonic airflow generated by 2D nozzle with and without an obstacle at the exit section
EP  - 113
IS  - 2
SP  - 107
VL  - 43
DO  - 10.5937/fmet1502107K
ER  - 

@article{
author = "Kostić, Olivera and Stefanović, Zoran and Kostić, Ivan",
year = "2015",
abstract = "Modeliranje složenih nadzvučnih strujnih polja korišćenjem računara predstavlja jedan od najvećih izazova u oblasti CFD analiza. U radu su predstavljeni prvi koraci u numeričkoj analizi takvog strujanja, generisanog konvergentno- divergentnim mlaznikom sa Mahovim brojem M = 2.6 na izlazu iz mlaznika. Cilj je bio postići dobra poklapanja sa raspoloživim eksperimentalnim podacima, dobijenim tokom ispitivanja u nadzvučnom aerotunelu instituta VTI Žarkovo, gde su ispitivane mogućnosti vektorisanja potiska mlaznika sa vazduhom kao radnim fluidom, postavljanjem različitih tipova prepreka na izlazu iza mlaznika. U radu se analiziraju slučajevi strujanja sa slobodnim izlazom i sa jednim izabranim tipom prepreke na izlazu iz mlaznika. Za oba slučaja korišćene su strukturirane proračunske mreže za rešavanje RANS jednačina sa k-w SST turbulentnim modelom. Nakon kvalitativnih i kvantitativnih poređenja sa raspoloživim eksperimentalnim rezultatima, utvrđena su dobra poklapanja, pri čemu je CFD analiza bila u mogućnosti da pruži i dodatne podatke o strujnom polju, koji nisu mereni tokom eksperimenata., Computational modeling of complex supersonic airflow patterns is one of the greatest challenges in the domain of CFD analyses. The paper presents initial steps in numerical analysis of such flow, generated by convergentdivergent nozzle with Mach number M = 2.6 at nozzle exit. The aim was to achieve good agreements with available experimental data, obtained during supersonic wind tunnel tests at VTI Žarkovo institute, where nozzle thrust vectoring possibilities had been investigated using air as test fluid, by placing different types of obstacles at the exit section. Paper is focussed on free exit flow, and flow with one selected obstacle type. Using structured mesh for both cases, the RANS equations with k-w SST turbulent model have been applied. After quantitative and qualitative comparisons with available experimental data, good agreements have been obtained, where CFD was also able to provide additional flowfield data, not measuted during experiments.",
publisher = "Univerzitet u Beogradu - Mašinski fakultet, Beograd",
journal = "FME Transactions",
title = "CFD modeliranje nadzvučne vazdušne struje generisane 2D mlaznikom sa preprekom i bez prepreke na izlazu, CFD modeling of supersonic airflow generated by 2D nozzle with and without an obstacle at the exit section",
pages = "113-107",
number = "2",
volume = "43",
doi = "10.5937/fmet1502107K"
}

Kostić, O., Stefanović, Z.,& Kostić, I.. (2015). CFD modeliranje nadzvučne vazdušne struje generisane 2D mlaznikom sa preprekom i bez prepreke na izlazu. in FME Transactions
Univerzitet u Beogradu - Mašinski fakultet, Beograd., 43(2), 107-113.
https://doi.org/10.5937/fmet1502107K

Kostić O, Stefanović Z, Kostić I. CFD modeliranje nadzvučne vazdušne struje generisane 2D mlaznikom sa preprekom i bez prepreke na izlazu. in FME Transactions. 2015;43(2):107-113.
doi:10.5937/fmet1502107K .

Kostić, Olivera, Stefanović, Zoran, Kostić, Ivan, "CFD modeliranje nadzvučne vazdušne struje generisane 2D mlaznikom sa preprekom i bez prepreke na izlazu" in FME Transactions, 43, no. 2 (2015):107-113,
https://doi.org/10.5937/fmet1502107K . .

TY  - JOUR
AU  - Kostić, Ivan
AU  - Stefanović, Zoran
AU  - Kostić, Olivera
PY  - 2014
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2000
AB  - Tokom aerodinamičkog projektovanja aviona, shodno njegovoj kategoriji i fazi razvoja projekta, potrebno je koristiti adekvatne proračunske metode i softverske alate. U slučaju lakih aviona, uobičajeno se koriste analitičke i semiempirijske metode u inicijalnoj fazi, kombinovane sa jednostavnim - neviskoznim CFD proračunskim modelima, dok se u kasnijim fazama obavljaju relativno kompleksne CFD analize sa uticajem viskoznosti. U današnje vreme se, u kategoriji lakih aviona, podrazumeva da savremeni proračunski alati za svaku od faza razvoja moraju biti adekvatno izabrani, tako da se njima dobijeni rezultati međusobno verifikuju i dopunjavaju. U radu su prikazane proračunske metode korišćene tokom aerodinamičke analize novog lakog aviona u različitim fazama njegovog razvoja i izvršeno je poređenje dobijenih rezultata, u cilju verifikacije ispunjenja navedenog uslova.
AB  - During the evolution of an airplane aerodynamic design, proper calculation methods and software tools should be utilized, which correspond to the airplane category and project development level. In case of light aircraft, the general trend is the application of analytical and semiempirical methods at the initial stages, combined with simplified - inviscid CFD computational models, and fairly complex viscous CFD analyses at higher design levels. At the present stage of light aviation development, it is assumed that the contemporary design tools for each of those steps should be appropriate enough, so that they actually verify and additionally fine-tune each other's results. This paper describes the calculation tools and methods applied during the aerodynamic analyses of a new light aircraft at different development stages, and compares the results obtained by them, with the aim to verify and support the above statement, considering light aircraft aerodynamic design.
PB  - Univerzitet u Beogradu - Mašinski fakultet, Beograd
T2  - FME Transactions
T1  - Aerodinamička analiza lakog aviona u različitim razvojnim fazama projekta
T1  - Aerodynamic analysis of a light aircraft at different design stages
EP  - 105
IS  - 2
SP  - 94
VL  - 42
DO  - 10.5937/fmet1402094K
ER  - 

@article{
author = "Kostić, Ivan and Stefanović, Zoran and Kostić, Olivera",
year = "2014",
abstract = "Tokom aerodinamičkog projektovanja aviona, shodno njegovoj kategoriji i fazi razvoja projekta, potrebno je koristiti adekvatne proračunske metode i softverske alate. U slučaju lakih aviona, uobičajeno se koriste analitičke i semiempirijske metode u inicijalnoj fazi, kombinovane sa jednostavnim - neviskoznim CFD proračunskim modelima, dok se u kasnijim fazama obavljaju relativno kompleksne CFD analize sa uticajem viskoznosti. U današnje vreme se, u kategoriji lakih aviona, podrazumeva da savremeni proračunski alati za svaku od faza razvoja moraju biti adekvatno izabrani, tako da se njima dobijeni rezultati međusobno verifikuju i dopunjavaju. U radu su prikazane proračunske metode korišćene tokom aerodinamičke analize novog lakog aviona u različitim fazama njegovog razvoja i izvršeno je poređenje dobijenih rezultata, u cilju verifikacije ispunjenja navedenog uslova., During the evolution of an airplane aerodynamic design, proper calculation methods and software tools should be utilized, which correspond to the airplane category and project development level. In case of light aircraft, the general trend is the application of analytical and semiempirical methods at the initial stages, combined with simplified - inviscid CFD computational models, and fairly complex viscous CFD analyses at higher design levels. At the present stage of light aviation development, it is assumed that the contemporary design tools for each of those steps should be appropriate enough, so that they actually verify and additionally fine-tune each other's results. This paper describes the calculation tools and methods applied during the aerodynamic analyses of a new light aircraft at different development stages, and compares the results obtained by them, with the aim to verify and support the above statement, considering light aircraft aerodynamic design.",
publisher = "Univerzitet u Beogradu - Mašinski fakultet, Beograd",
journal = "FME Transactions",
title = "Aerodinamička analiza lakog aviona u različitim razvojnim fazama projekta, Aerodynamic analysis of a light aircraft at different design stages",
pages = "105-94",
number = "2",
volume = "42",
doi = "10.5937/fmet1402094K"
}

Kostić, I., Stefanović, Z.,& Kostić, O.. (2014). Aerodinamička analiza lakog aviona u različitim razvojnim fazama projekta. in FME Transactions
Univerzitet u Beogradu - Mašinski fakultet, Beograd., 42(2), 94-105.
https://doi.org/10.5937/fmet1402094K

Kostić I, Stefanović Z, Kostić O. Aerodinamička analiza lakog aviona u različitim razvojnim fazama projekta. in FME Transactions. 2014;42(2):94-105.
doi:10.5937/fmet1402094K .

Kostić, Ivan, Stefanović, Zoran, Kostić, Olivera, "Aerodinamička analiza lakog aviona u različitim razvojnim fazama projekta" in FME Transactions, 42, no. 2 (2014):94-105,
https://doi.org/10.5937/fmet1402094K . .

TY  - JOUR
AU  - Svorcan, Jelena
AU  - Stupar, Slobodan
AU  - Komarov, Dragan
AU  - Peković, Ognjen
AU  - Kostić, Ivan
PY  - 2013
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/1677
AB  - Small-scale vertical axis wind turbines are regarded today as an attractive source of green energy, still insufficiently implemented and tested. This paper presents a fast design methodology of such a VAWT, in terms of choosing its main parameters: airfoil, rotor diameter and solidity. For obtaining generated power of each considered geometrical model at different undisturbed wind velocities and rotor angular velocities two models were used - momentum and vortex-wake model, combined with experimentally measured airfoil data (airfoil lift and drag coefficients). Even though the former model is simpler, it is the most utilized model, known to provide good results in stationary working regimes. Both models still present fairly accurate and fast tools for computation and optimization, particularly useful in the phase of conceptual design. In this research, the use of the momentum model resulted in determination of the maximal power coefficient, optimal-and minimal freestream velocity for every considered VAWT model. From these output parameters, a selection of the optimal geometric model was done, and a more detailed transient analysis and flow representation around the selected solution was obtained by the vortex-wake model. The results obtained by the two used computational models coincide satisfactorily.
PB  - Korean Soc Mechanical Engineers, Seoul
T2  - Journal of Mechanical Science and Technology
T1  - Aerodynamic design and analysis of a small-scale vertical axis wind turbine
EP  - 2373
IS  - 8
SP  - 2367
VL  - 27
DO  - 10.1007/s12206-013-0621-x
ER  - 

@article{
author = "Svorcan, Jelena and Stupar, Slobodan and Komarov, Dragan and Peković, Ognjen and Kostić, Ivan",
year = "2013",
abstract = "Small-scale vertical axis wind turbines are regarded today as an attractive source of green energy, still insufficiently implemented and tested. This paper presents a fast design methodology of such a VAWT, in terms of choosing its main parameters: airfoil, rotor diameter and solidity. For obtaining generated power of each considered geometrical model at different undisturbed wind velocities and rotor angular velocities two models were used - momentum and vortex-wake model, combined with experimentally measured airfoil data (airfoil lift and drag coefficients). Even though the former model is simpler, it is the most utilized model, known to provide good results in stationary working regimes. Both models still present fairly accurate and fast tools for computation and optimization, particularly useful in the phase of conceptual design. In this research, the use of the momentum model resulted in determination of the maximal power coefficient, optimal-and minimal freestream velocity for every considered VAWT model. From these output parameters, a selection of the optimal geometric model was done, and a more detailed transient analysis and flow representation around the selected solution was obtained by the vortex-wake model. The results obtained by the two used computational models coincide satisfactorily.",
publisher = "Korean Soc Mechanical Engineers, Seoul",
journal = "Journal of Mechanical Science and Technology",
title = "Aerodynamic design and analysis of a small-scale vertical axis wind turbine",
pages = "2373-2367",
number = "8",
volume = "27",
doi = "10.1007/s12206-013-0621-x"
}

Svorcan, J., Stupar, S., Komarov, D., Peković, O.,& Kostić, I.. (2013). Aerodynamic design and analysis of a small-scale vertical axis wind turbine. in Journal of Mechanical Science and Technology
Korean Soc Mechanical Engineers, Seoul., 27(8), 2367-2373.
https://doi.org/10.1007/s12206-013-0621-x

Svorcan J, Stupar S, Komarov D, Peković O, Kostić I. Aerodynamic design and analysis of a small-scale vertical axis wind turbine. in Journal of Mechanical Science and Technology. 2013;27(8):2367-2373.
doi:10.1007/s12206-013-0621-x .

Svorcan, Jelena, Stupar, Slobodan, Komarov, Dragan, Peković, Ognjen, Kostić, Ivan, "Aerodynamic design and analysis of a small-scale vertical axis wind turbine" in Journal of Mechanical Science and Technology, 27, no. 8 (2013):2367-2373,
https://doi.org/10.1007/s12206-013-0621-x . .

TY  - JOUR
AU  - Kostić, Ivan
AU  - Stefanović, Zoran
AU  - Petrović, Zlatko
AU  - Kostić, Olivera
AU  - Essari, Abdulhakim
PY  - 2013
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/1796
AB  - The paper is focused on the preliminary aerodynamic analyses of a new light aircraft in symmetrical flight configurations. Initial calculations have been done using a 3D vortex lattice method. Since this method is based on inviscid flow concept, the non-linear calibration diagrams for the effectiveness and circulation of control surfaces have been derived from wind tunnel test data of an existing airplane. These calibration functions have been interpolated for a new light aircraft geometry, and analyses of lift and moment coefficients with different flaps and elevator deflections have been performed. Deflected flaps and elevator generate local lift redistributions which contribute to the induced drag, even at angles of attack when the total airplane lift is zero, which has been successfully determined by the applied CFD model. Parasite drag components, omitted by CFD calculations, have been obtained using DVL and Datcom methods and superimposed with CFD results, giving complete new aircraft polars, which have been successfully applied in longitudinal stability and basic performance estimates.
PB  - Faculty of Mechanical Engineering in Slavonski Brod, Faculty of Electrical Engineering in Osijek, Faculty of Civil Engineering in Osijek
T2  - Tehnički vjesnik
T1  - Hybrid approach in the initial aerodynamic, stability and performance calculations of a light airplane
EP  - 614
IS  - 4
SP  - 605
VL  - 20
UR  - https://hdl.handle.net/21.15107/rcub_machinery_1796
ER  - 

@article{
author = "Kostić, Ivan and Stefanović, Zoran and Petrović, Zlatko and Kostić, Olivera and Essari, Abdulhakim",
year = "2013",
abstract = "The paper is focused on the preliminary aerodynamic analyses of a new light aircraft in symmetrical flight configurations. Initial calculations have been done using a 3D vortex lattice method. Since this method is based on inviscid flow concept, the non-linear calibration diagrams for the effectiveness and circulation of control surfaces have been derived from wind tunnel test data of an existing airplane. These calibration functions have been interpolated for a new light aircraft geometry, and analyses of lift and moment coefficients with different flaps and elevator deflections have been performed. Deflected flaps and elevator generate local lift redistributions which contribute to the induced drag, even at angles of attack when the total airplane lift is zero, which has been successfully determined by the applied CFD model. Parasite drag components, omitted by CFD calculations, have been obtained using DVL and Datcom methods and superimposed with CFD results, giving complete new aircraft polars, which have been successfully applied in longitudinal stability and basic performance estimates.",
publisher = "Faculty of Mechanical Engineering in Slavonski Brod, Faculty of Electrical Engineering in Osijek, Faculty of Civil Engineering in Osijek",
journal = "Tehnički vjesnik",
title = "Hybrid approach in the initial aerodynamic, stability and performance calculations of a light airplane",
pages = "614-605",
number = "4",
volume = "20",
url = "https://hdl.handle.net/21.15107/rcub_machinery_1796"
}

Kostić, I., Stefanović, Z., Petrović, Z., Kostić, O.,& Essari, A.. (2013). Hybrid approach in the initial aerodynamic, stability and performance calculations of a light airplane. in Tehnički vjesnik
Faculty of Mechanical Engineering in Slavonski Brod, Faculty of Electrical Engineering in Osijek, Faculty of Civil Engineering in Osijek., 20(4), 605-614.
https://hdl.handle.net/21.15107/rcub_machinery_1796

Kostić I, Stefanović Z, Petrović Z, Kostić O, Essari A. Hybrid approach in the initial aerodynamic, stability and performance calculations of a light airplane. in Tehnički vjesnik. 2013;20(4):605-614.
https://hdl.handle.net/21.15107/rcub_machinery_1796 .

Kostić, Ivan, Stefanović, Zoran, Petrović, Zlatko, Kostić, Olivera, Essari, Abdulhakim, "Hybrid approach in the initial aerodynamic, stability and performance calculations of a light airplane" in Tehnički vjesnik, 20, no. 4 (2013):605-614,
https://hdl.handle.net/21.15107/rcub_machinery_1796 .

TY  - JOUR
AU  - Stefanović, Zoran
AU  - Kostić, Ivan
AU  - Kostić, Olivera
PY  - 2012
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/1598
AB  - In the preliminary aerodynamic aircraft design, optimum calculation methods should be used, which enable engineers to perform a vast number of test runs in a reasonably short time. Such tools should not only be fairly simple but also reliable. In the first part, this paper briefly presents aerodynamic analyses performed by a 3D vortex lattice method (VLM), with an aim to verify its capabilities to give results that coincide well with the experimental data of an existing airplane. Since this computational model is based on inviscid flow concept, effectiveness of control surfaces and flaps are inherently overestimated. In order to compensate for the omitted boundary layer influence, a set of calibration diagrams for effectiveness and circulation influence has been successfully derived and good agreements with wind tunnel test data have been achieved. After several necessary adjustments, calibration functions have been applied to VLM analysis within a new light aircraft conceptual study. Those results have been compared with results obtained by well known Datcom method and verygood agreements have been achieved, proving that VLM computations with properly defined calibration functions can be both efficient and reliable tools in preliminary aerodynamic design.
T2  - Engineering Review
T1  - Efficient evaluation of preliminary aerodynamic characteristics of light trainer aircraft
EP  - 56
IS  - 1
SP  - 49
VL  - 32
UR  - https://hdl.handle.net/21.15107/rcub_machinery_1598
ER  - 

@article{
author = "Stefanović, Zoran and Kostić, Ivan and Kostić, Olivera",
year = "2012",
abstract = "In the preliminary aerodynamic aircraft design, optimum calculation methods should be used, which enable engineers to perform a vast number of test runs in a reasonably short time. Such tools should not only be fairly simple but also reliable. In the first part, this paper briefly presents aerodynamic analyses performed by a 3D vortex lattice method (VLM), with an aim to verify its capabilities to give results that coincide well with the experimental data of an existing airplane. Since this computational model is based on inviscid flow concept, effectiveness of control surfaces and flaps are inherently overestimated. In order to compensate for the omitted boundary layer influence, a set of calibration diagrams for effectiveness and circulation influence has been successfully derived and good agreements with wind tunnel test data have been achieved. After several necessary adjustments, calibration functions have been applied to VLM analysis within a new light aircraft conceptual study. Those results have been compared with results obtained by well known Datcom method and verygood agreements have been achieved, proving that VLM computations with properly defined calibration functions can be both efficient and reliable tools in preliminary aerodynamic design.",
journal = "Engineering Review",
title = "Efficient evaluation of preliminary aerodynamic characteristics of light trainer aircraft",
pages = "56-49",
number = "1",
volume = "32",
url = "https://hdl.handle.net/21.15107/rcub_machinery_1598"
}

Stefanović, Z., Kostić, I.,& Kostić, O.. (2012). Efficient evaluation of preliminary aerodynamic characteristics of light trainer aircraft. in Engineering Review, 32(1), 49-56.
https://hdl.handle.net/21.15107/rcub_machinery_1598

Stefanović Z, Kostić I, Kostić O. Efficient evaluation of preliminary aerodynamic characteristics of light trainer aircraft. in Engineering Review. 2012;32(1):49-56.
https://hdl.handle.net/21.15107/rcub_machinery_1598 .

Stefanović, Zoran, Kostić, Ivan, Kostić, Olivera, "Efficient evaluation of preliminary aerodynamic characteristics of light trainer aircraft" in Engineering Review, 32, no. 1 (2012):49-56,
https://hdl.handle.net/21.15107/rcub_machinery_1598 .

TY  - CONF
AU  - Stefanović, Zoran
AU  - Kostić, Ivan
AU  - Kostić, Olivera
PY  - 2012
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/1447
AB  - The paper is confined to the preliminary aerodynamic analyses of a new light aircraft with different combinations of flaps and elevator deflections, which correspond to the symmetrical flight conditions. Initial calculations have been performed using a 3D vortex lattice method. Since the applied computational model is based on inviscid flow concept, the non-linear calibration diagrams for the effectiveness of control surfaces and circulation influence have been derived from wind tunnel test data for an existing airplane. Then the calibration functions have been interpolated for a new light aircraft, and a wide scope of analyses for lift and moment coefficients with different flaps and elevator deflections has been performed Of special importance was the determination of lift-induced drag polars. Namely, deflected flaps and elevator generate local lift distributions which contribute to the induced drag, even at angles of attack when the total airplane 10 is zero, which has been successfully determined by the applied CFD model. Parasite drag components, omitted by CFD calculations, have been estimated using DVL, Datcom and Douglas methods and superimposed with the induced drag results, giving complete diagrams for the new aircraft in different symmetric flight configurations.
PB  - Univ Novi Sad, Fac Tech Sci, Adeko, Novi Sad
C3  - Machine and Industrial Design in Mechanical Engineering, Seventh International Symposium, Kod 2012
T1  - Primary aerodynamic analyses of a new light aircraft in symmetrical flight configurations
EP  - 104
SP  - 97
UR  - https://hdl.handle.net/21.15107/rcub_machinery_1447
ER  - 

@conference{
author = "Stefanović, Zoran and Kostić, Ivan and Kostić, Olivera",
year = "2012",
abstract = "The paper is confined to the preliminary aerodynamic analyses of a new light aircraft with different combinations of flaps and elevator deflections, which correspond to the symmetrical flight conditions. Initial calculations have been performed using a 3D vortex lattice method. Since the applied computational model is based on inviscid flow concept, the non-linear calibration diagrams for the effectiveness of control surfaces and circulation influence have been derived from wind tunnel test data for an existing airplane. Then the calibration functions have been interpolated for a new light aircraft, and a wide scope of analyses for lift and moment coefficients with different flaps and elevator deflections has been performed Of special importance was the determination of lift-induced drag polars. Namely, deflected flaps and elevator generate local lift distributions which contribute to the induced drag, even at angles of attack when the total airplane 10 is zero, which has been successfully determined by the applied CFD model. Parasite drag components, omitted by CFD calculations, have been estimated using DVL, Datcom and Douglas methods and superimposed with the induced drag results, giving complete diagrams for the new aircraft in different symmetric flight configurations.",
publisher = "Univ Novi Sad, Fac Tech Sci, Adeko, Novi Sad",
journal = "Machine and Industrial Design in Mechanical Engineering, Seventh International Symposium, Kod 2012",
title = "Primary aerodynamic analyses of a new light aircraft in symmetrical flight configurations",
pages = "104-97",
url = "https://hdl.handle.net/21.15107/rcub_machinery_1447"
}

Stefanović, Z., Kostić, I.,& Kostić, O.. (2012). Primary aerodynamic analyses of a new light aircraft in symmetrical flight configurations. in Machine and Industrial Design in Mechanical Engineering, Seventh International Symposium, Kod 2012
Univ Novi Sad, Fac Tech Sci, Adeko, Novi Sad., 97-104.
https://hdl.handle.net/21.15107/rcub_machinery_1447

Stefanović Z, Kostić I, Kostić O. Primary aerodynamic analyses of a new light aircraft in symmetrical flight configurations. in Machine and Industrial Design in Mechanical Engineering, Seventh International Symposium, Kod 2012. 2012;:97-104.
https://hdl.handle.net/21.15107/rcub_machinery_1447 .

Stefanović, Zoran, Kostić, Ivan, Kostić, Olivera, "Primary aerodynamic analyses of a new light aircraft in symmetrical flight configurations" in Machine and Industrial Design in Mechanical Engineering, Seventh International Symposium, Kod 2012 (2012):97-104,
https://hdl.handle.net/21.15107/rcub_machinery_1447 .

TY  - JOUR
AU  - Simonović, Aleksandar
AU  - Kostić, Ivan
AU  - Stupar, Slobodan
AU  - Petrović, Z.
PY  - 2012
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/1444
AB  - Experimental acquisition and verification of structural properties of an actual helicopter main rotor blade segment have been done with an aim to validate the capability of bonded joints of these structural elements to sustain the most dominant dynamic loads in forward flight, for the assigned blade's life time. It was also one of the qualitative tests of the newly applied rotor blade hybrid structure production technology, consisting of a metal spar and 21 plastic composite segments, bonded to it after the polymerization process. Because of the structural similarity of the segments, only the most highly loaded 21st segment and adjacent spar section were investigated, as representative in this particular sense. This has enabled remarkable reduction both in time and funds required for the design and construction of the test facility. This paper is focused on the demonstration of usage of fairly low-cost experimental infrastructure for that purpose, and also provides the designers and engineers with some examples and guidelines of how it is possible to conduct experimental verifications of the properties of similar, both aeronautical and non-aeronautical hybrid structures and joints, exposed to the long-lasting dynamic loads. Tests presented in this paper were only a part of a very wide test campaign, mostly undertaken on the entire new hybrid blade structures, both on the ground and in flight, before they have been put to operational service.
PB  - Springer, New York
T2  - Experimental Techniques
T1  - Laboratory Tests of a Hybrid Metal-Composite Transport Helicopter Blade Segment
EP  - 32
IS  - 3
SP  - 22
VL  - 36
DO  - 10.1111/j.1747-1567.2011.00708.x
ER  - 

@article{
author = "Simonović, Aleksandar and Kostić, Ivan and Stupar, Slobodan and Petrović, Z.",
year = "2012",
abstract = "Experimental acquisition and verification of structural properties of an actual helicopter main rotor blade segment have been done with an aim to validate the capability of bonded joints of these structural elements to sustain the most dominant dynamic loads in forward flight, for the assigned blade's life time. It was also one of the qualitative tests of the newly applied rotor blade hybrid structure production technology, consisting of a metal spar and 21 plastic composite segments, bonded to it after the polymerization process. Because of the structural similarity of the segments, only the most highly loaded 21st segment and adjacent spar section were investigated, as representative in this particular sense. This has enabled remarkable reduction both in time and funds required for the design and construction of the test facility. This paper is focused on the demonstration of usage of fairly low-cost experimental infrastructure for that purpose, and also provides the designers and engineers with some examples and guidelines of how it is possible to conduct experimental verifications of the properties of similar, both aeronautical and non-aeronautical hybrid structures and joints, exposed to the long-lasting dynamic loads. Tests presented in this paper were only a part of a very wide test campaign, mostly undertaken on the entire new hybrid blade structures, both on the ground and in flight, before they have been put to operational service.",
publisher = "Springer, New York",
journal = "Experimental Techniques",
title = "Laboratory Tests of a Hybrid Metal-Composite Transport Helicopter Blade Segment",
pages = "32-22",
number = "3",
volume = "36",
doi = "10.1111/j.1747-1567.2011.00708.x"
}

Simonović, A., Kostić, I., Stupar, S.,& Petrović, Z.. (2012). Laboratory Tests of a Hybrid Metal-Composite Transport Helicopter Blade Segment. in Experimental Techniques
Springer, New York., 36(3), 22-32.
https://doi.org/10.1111/j.1747-1567.2011.00708.x

Simonović A, Kostić I, Stupar S, Petrović Z. Laboratory Tests of a Hybrid Metal-Composite Transport Helicopter Blade Segment. in Experimental Techniques. 2012;36(3):22-32.
doi:10.1111/j.1747-1567.2011.00708.x .

Simonović, Aleksandar, Kostić, Ivan, Stupar, Slobodan, Petrović, Z., "Laboratory Tests of a Hybrid Metal-Composite Transport Helicopter Blade Segment" in Experimental Techniques, 36, no. 3 (2012):22-32,
https://doi.org/10.1111/j.1747-1567.2011.00708.x . .

TY  - JOUR
AU  - Petrović, Zlatko
AU  - Stupar, Slobodan
AU  - Kostić, Ivan
AU  - Simonović, Aleksandar
PY  - 2010
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/1001
AB  - Promising solutions for the problem of the extensively time-consuming modern urban transportation has been found in the use of light and very light helicopters. This paper presents a part of the preliminary design methodology, compiled at the Faculty of Mechanical Engineering, University of Belgrade and includes performance calculations of such helicopters. Due to limited budgets and an extremely demanding process of helicopter development, it is highly significantt that during all development stages reliable performance estimates are obtained in order to ensure assigned operational requirements. The scope of this paper is confined to the preliminary design stage, where it is customary to substitute the very complex helicopter rotor dynamics with its averaged mechanical and aerodynamic characteristics and apply certain empirically verified simplifications. Based on this approach, the independent, efficient and reliable computer programs for the calculation of different performance characteristics have been developed. In addition to their application on an actual on-going project, they have also been applied on several existing helicopters of a similar class for a more accurate determination of the empirical input parameters. The applied methodology and obtained results have been presented, verifying the overall algorithm efficiency.
T2  - Strojniski Vestnik/Journal of Mechanical Engineering
T1  - Determination of a Light Helicopter Flight Performance at the Preliminary Design Stage
EP  - 543
IS  - 9
SP  - 535
VL  - 56
UR  - https://hdl.handle.net/21.15107/rcub_machinery_1001
ER  - 

@article{
author = "Petrović, Zlatko and Stupar, Slobodan and Kostić, Ivan and Simonović, Aleksandar",
year = "2010",
abstract = "Promising solutions for the problem of the extensively time-consuming modern urban transportation has been found in the use of light and very light helicopters. This paper presents a part of the preliminary design methodology, compiled at the Faculty of Mechanical Engineering, University of Belgrade and includes performance calculations of such helicopters. Due to limited budgets and an extremely demanding process of helicopter development, it is highly significantt that during all development stages reliable performance estimates are obtained in order to ensure assigned operational requirements. The scope of this paper is confined to the preliminary design stage, where it is customary to substitute the very complex helicopter rotor dynamics with its averaged mechanical and aerodynamic characteristics and apply certain empirically verified simplifications. Based on this approach, the independent, efficient and reliable computer programs for the calculation of different performance characteristics have been developed. In addition to their application on an actual on-going project, they have also been applied on several existing helicopters of a similar class for a more accurate determination of the empirical input parameters. The applied methodology and obtained results have been presented, verifying the overall algorithm efficiency.",
journal = "Strojniski Vestnik/Journal of Mechanical Engineering",
title = "Determination of a Light Helicopter Flight Performance at the Preliminary Design Stage",
pages = "543-535",
number = "9",
volume = "56",
url = "https://hdl.handle.net/21.15107/rcub_machinery_1001"
}

Petrović, Z., Stupar, S., Kostić, I.,& Simonović, A.. (2010). Determination of a Light Helicopter Flight Performance at the Preliminary Design Stage. in Strojniski Vestnik/Journal of Mechanical Engineering, 56(9), 535-543.
https://hdl.handle.net/21.15107/rcub_machinery_1001

Petrović Z, Stupar S, Kostić I, Simonović A. Determination of a Light Helicopter Flight Performance at the Preliminary Design Stage. in Strojniski Vestnik/Journal of Mechanical Engineering. 2010;56(9):535-543.
https://hdl.handle.net/21.15107/rcub_machinery_1001 .

Petrović, Zlatko, Stupar, Slobodan, Kostić, Ivan, Simonović, Aleksandar, "Determination of a Light Helicopter Flight Performance at the Preliminary Design Stage" in Strojniski Vestnik/Journal of Mechanical Engineering, 56, no. 9 (2010):535-543,
https://hdl.handle.net/21.15107/rcub_machinery_1001 .

TY  - JOUR
AU  - Stefanović, Zoran
AU  - Kostić, Ivan
PY  - 2010
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/991
AB  - High lift-to-drag ratios of the contemporary sailplanes make them the most energy efficient flying vehicles. On the other hand, this capability may become their serious disadvantage during the landing, if their aerodynamic deceleration devices become inoperable in flight. Not being able to dissipate the excess energy quickly when close to the ground, they may fly over the available landing ground and finish up in front of the obstacles, with still too much energy to land and not enough to fly over them. Beside the sideslipping flight in final, where energy is dissipated through the increased sideforce drag, another solution to this problem has been offered in a number of papers. By numerical analyses they have shown that landing distance in such cases could be minimized using rather complex oscillating flight paths in vertical plane. Although relevant distance reductions could be achieved through them, performing such paths in practice would require exceptional piloting skills. Instead of that, in this paper much simpler approach profiles have been analyzed, based on two types of cosine speed variations with constant periods and amplitudes, which could be flown by pilots of average flying experience. After establishing a quick convergence algorithm, numerical solutions for several typical cases, belonging to two general speed variation types, have been presented. The same initial and terminal reference energy states have been used. Although the distance reductions are smaller than obtained by distance-minimizing techniques, operational simplicity of presented techniques and some specific advantages prove them valuable within this categoiy of problems.
T2  - Strojniski Vestnik/Journal of Mechanical Engineering
T1  - Analysis of the Sailplane Final Approaches Performed by Cosine-Law Speed Variations
EP  - 446
IS  - 7-8
SP  - 436
VL  - 56
UR  - https://hdl.handle.net/21.15107/rcub_machinery_991
ER  - 

@article{
author = "Stefanović, Zoran and Kostić, Ivan",
year = "2010",
abstract = "High lift-to-drag ratios of the contemporary sailplanes make them the most energy efficient flying vehicles. On the other hand, this capability may become their serious disadvantage during the landing, if their aerodynamic deceleration devices become inoperable in flight. Not being able to dissipate the excess energy quickly when close to the ground, they may fly over the available landing ground and finish up in front of the obstacles, with still too much energy to land and not enough to fly over them. Beside the sideslipping flight in final, where energy is dissipated through the increased sideforce drag, another solution to this problem has been offered in a number of papers. By numerical analyses they have shown that landing distance in such cases could be minimized using rather complex oscillating flight paths in vertical plane. Although relevant distance reductions could be achieved through them, performing such paths in practice would require exceptional piloting skills. Instead of that, in this paper much simpler approach profiles have been analyzed, based on two types of cosine speed variations with constant periods and amplitudes, which could be flown by pilots of average flying experience. After establishing a quick convergence algorithm, numerical solutions for several typical cases, belonging to two general speed variation types, have been presented. The same initial and terminal reference energy states have been used. Although the distance reductions are smaller than obtained by distance-minimizing techniques, operational simplicity of presented techniques and some specific advantages prove them valuable within this categoiy of problems.",
journal = "Strojniski Vestnik/Journal of Mechanical Engineering",
title = "Analysis of the Sailplane Final Approaches Performed by Cosine-Law Speed Variations",
pages = "446-436",
number = "7-8",
volume = "56",
url = "https://hdl.handle.net/21.15107/rcub_machinery_991"
}

Stefanović, Z.,& Kostić, I.. (2010). Analysis of the Sailplane Final Approaches Performed by Cosine-Law Speed Variations. in Strojniski Vestnik/Journal of Mechanical Engineering, 56(7-8), 436-446.
https://hdl.handle.net/21.15107/rcub_machinery_991

Stefanović Z, Kostić I. Analysis of the Sailplane Final Approaches Performed by Cosine-Law Speed Variations. in Strojniski Vestnik/Journal of Mechanical Engineering. 2010;56(7-8):436-446.
https://hdl.handle.net/21.15107/rcub_machinery_991 .

Stefanović, Zoran, Kostić, Ivan, "Analysis of the Sailplane Final Approaches Performed by Cosine-Law Speed Variations" in Strojniski Vestnik/Journal of Mechanical Engineering, 56, no. 7-8 (2010):436-446,
https://hdl.handle.net/21.15107/rcub_machinery_991 .

TY  - CONF
AU  - Stefanović, Zoran
AU  - Kostić, Ivan
PY  - 2010
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/1122
AB  - In initial stages of aircraft aerodynamic design, it is common practice to apply fairly simple but reliable computer packages, that enable engineers to perform a large number of test runs in a reasonably short time. This paper is mainly focused on the tests done by such software, based on 3D vortex-lattice method, with an aim to verb its capabilities to give results that properly coincide with the existing airplane's data. For software reliability tests, the popular domestic Utva-75 light aircraft has been selected, for which a wide scope of wind tunnel test results exist. Since the applied computational model is based on inviscid flow concept, effectiveness of the flaps and control surfaces, deflected to angles larger than 5 degrees, are inherently overestimated. In order to compensate for the omitted boundary layer influence and separation effects, a set of calibration options has been properly applied, the non-linear calibration diagrams for their effectiveness and circulation influence have been derived and very good agreements with wind tunnel data have been achieved. The actual aim of defining software calibration functions is to enable efficient prediction and optimization of the large number of aerodynamic characteristics for a new airplane of the same category, during the first stages of its conceptual analysis.
PB  - Univ Novi Sad, Fac Tech Sci, Adeko, Novi Sad
C3  - Sixth International Symposium About Forming and Design in Mechanical Engineering
T1  - A vortex lattice method application in aerodynamic analysis and design of light aircraft
EP  - 92
SP  - 85
UR  - https://hdl.handle.net/21.15107/rcub_machinery_1122
ER  - 

@conference{
author = "Stefanović, Zoran and Kostić, Ivan",
year = "2010",
abstract = "In initial stages of aircraft aerodynamic design, it is common practice to apply fairly simple but reliable computer packages, that enable engineers to perform a large number of test runs in a reasonably short time. This paper is mainly focused on the tests done by such software, based on 3D vortex-lattice method, with an aim to verb its capabilities to give results that properly coincide with the existing airplane's data. For software reliability tests, the popular domestic Utva-75 light aircraft has been selected, for which a wide scope of wind tunnel test results exist. Since the applied computational model is based on inviscid flow concept, effectiveness of the flaps and control surfaces, deflected to angles larger than 5 degrees, are inherently overestimated. In order to compensate for the omitted boundary layer influence and separation effects, a set of calibration options has been properly applied, the non-linear calibration diagrams for their effectiveness and circulation influence have been derived and very good agreements with wind tunnel data have been achieved. The actual aim of defining software calibration functions is to enable efficient prediction and optimization of the large number of aerodynamic characteristics for a new airplane of the same category, during the first stages of its conceptual analysis.",
publisher = "Univ Novi Sad, Fac Tech Sci, Adeko, Novi Sad",
journal = "Sixth International Symposium About Forming and Design in Mechanical Engineering",
title = "A vortex lattice method application in aerodynamic analysis and design of light aircraft",
pages = "92-85",
url = "https://hdl.handle.net/21.15107/rcub_machinery_1122"
}

Stefanović, Z.,& Kostić, I.. (2010). A vortex lattice method application in aerodynamic analysis and design of light aircraft. in Sixth International Symposium About Forming and Design in Mechanical Engineering
Univ Novi Sad, Fac Tech Sci, Adeko, Novi Sad., 85-92.
https://hdl.handle.net/21.15107/rcub_machinery_1122

Stefanović Z, Kostić I. A vortex lattice method application in aerodynamic analysis and design of light aircraft. in Sixth International Symposium About Forming and Design in Mechanical Engineering. 2010;:85-92.
https://hdl.handle.net/21.15107/rcub_machinery_1122 .

Stefanović, Zoran, Kostić, Ivan, "A vortex lattice method application in aerodynamic analysis and design of light aircraft" in Sixth International Symposium About Forming and Design in Mechanical Engineering (2010):85-92,
https://hdl.handle.net/21.15107/rcub_machinery_1122 .

TY  - CONF
AU  - Peković, Ognjen
AU  - Kostić, Ivan
AU  - Simonović, Aleksandar
PY  - 2009
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/902
PB  - Institute of Mechanical Engineering
C3  - 26th Danubia-Adria Symposium on Advances in Experimental Mechanics
T1  - Fatigue testing of bonded connection between aluminium spar and plastic composite pocket of transport helicopter main rotor blade
EP  - 178
SP  - 177
UR  - https://hdl.handle.net/21.15107/rcub_machinery_902
ER  - 

@conference{
author = "Peković, Ognjen and Kostić, Ivan and Simonović, Aleksandar",
year = "2009",
publisher = "Institute of Mechanical Engineering",
journal = "26th Danubia-Adria Symposium on Advances in Experimental Mechanics",
title = "Fatigue testing of bonded connection between aluminium spar and plastic composite pocket of transport helicopter main rotor blade",
pages = "178-177",
url = "https://hdl.handle.net/21.15107/rcub_machinery_902"
}

Peković, O., Kostić, I.,& Simonović, A.. (2009). Fatigue testing of bonded connection between aluminium spar and plastic composite pocket of transport helicopter main rotor blade. in 26th Danubia-Adria Symposium on Advances in Experimental Mechanics
Institute of Mechanical Engineering., 177-178.
https://hdl.handle.net/21.15107/rcub_machinery_902

Peković O, Kostić I, Simonović A. Fatigue testing of bonded connection between aluminium spar and plastic composite pocket of transport helicopter main rotor blade. in 26th Danubia-Adria Symposium on Advances in Experimental Mechanics. 2009;:177-178.
https://hdl.handle.net/21.15107/rcub_machinery_902 .

Peković, Ognjen, Kostić, Ivan, Simonović, Aleksandar, "Fatigue testing of bonded connection between aluminium spar and plastic composite pocket of transport helicopter main rotor blade" in 26th Danubia-Adria Symposium on Advances in Experimental Mechanics (2009):177-178,
https://hdl.handle.net/21.15107/rcub_machinery_902 .

TY  - JOUR
AU  - Stefanović, Zoran
AU  - Kostić, Ivan
PY  - 2007
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/722
AB  - Ukoliko iz bilo kog tehničkog razloga vazdušne kočnice prestanu da funkcionišu tokom leta, najkritičnija faza u proceduri sletanja jedrilice je finalni prilaz. Pored leta sa bočnim klizanjem, kada se disipacija energije vrši kroz povećanje bočne sile otpora, drugo moguće rešenje ovog problema je ponuđeno u literaturi, gde je pokazano da se dužina prilaza može minimizirati primenom složenih oscilatornih putanja leta. Međutim, let po takvim putanjama zahteva izuzetno letačko umeće. Nasuprot tome, u ovom radu izvršena je analiza jednostavnijih prilaznih putanja, baziranih na harmonijskim promenama brzine, koje je mnogo lakše operativno reprodukovati u letu. U radu je prikazan proračunski algoritam koji omogućava brzu konvergenciju rešenja i analizirana su numerička rešenja za nekoliko tipičnih slučajeva. Kao primer korišćeni su podaci za jedrilicu Vuk-T. Dobijeni rezultati pokazuju nešto manja skraćenja putanja, ali jednostavnost primene u praksi i veća bezbednost predloženih tehnika letenja čini ih korisnim rešenjima u slučaju pomenutih problema.
AB  - When for any technical reason spoilers become inoperable in flight, the most critical phase of a sailplane landing procedure is final approach. Besides the sideslipping flight possibility, where energy is dissipated through the increased sideforce drag, another solution for this problem has been offered in literature, showing that the landing distance could be minimized using rather complex oscillating flight paths. The problem is that performing such paths in practice would require exceptional piloting skills. Instead of that, in this paper much simpler approach profiles have been analyzed, based on the simple harmonic speed variations, which could much easier be reproduced in practice. After establishing a quick convergence algorithm, numerical solutions for several typical cases, taking the Vuk-T sailplane as an example, have been presented. Although distance reductions are generally smaller than obtained by distance-minimizing techniques, their operational simplicity and higher safety prove them as valuable solutions for this kind of problems.
PB  - Univerzitet u Beogradu - Mašinski fakultet, Beograd
T2  - FME Transactions
T1  - Uticaj prostih harmonijskih promena brzine ha oblik i dužinu prilazne putanje jedrilice Vuk-T
T1  - Influence of simple harmonic speed variations on the Vuk-T sailplane approach paths and distances
EP  - 75
IS  - 2
SP  - 69
VL  - 35
UR  - https://hdl.handle.net/21.15107/rcub_machinery_722
ER  - 

@article{
author = "Stefanović, Zoran and Kostić, Ivan",
year = "2007",
abstract = "Ukoliko iz bilo kog tehničkog razloga vazdušne kočnice prestanu da funkcionišu tokom leta, najkritičnija faza u proceduri sletanja jedrilice je finalni prilaz. Pored leta sa bočnim klizanjem, kada se disipacija energije vrši kroz povećanje bočne sile otpora, drugo moguće rešenje ovog problema je ponuđeno u literaturi, gde je pokazano da se dužina prilaza može minimizirati primenom složenih oscilatornih putanja leta. Međutim, let po takvim putanjama zahteva izuzetno letačko umeće. Nasuprot tome, u ovom radu izvršena je analiza jednostavnijih prilaznih putanja, baziranih na harmonijskim promenama brzine, koje je mnogo lakše operativno reprodukovati u letu. U radu je prikazan proračunski algoritam koji omogućava brzu konvergenciju rešenja i analizirana su numerička rešenja za nekoliko tipičnih slučajeva. Kao primer korišćeni su podaci za jedrilicu Vuk-T. Dobijeni rezultati pokazuju nešto manja skraćenja putanja, ali jednostavnost primene u praksi i veća bezbednost predloženih tehnika letenja čini ih korisnim rešenjima u slučaju pomenutih problema., When for any technical reason spoilers become inoperable in flight, the most critical phase of a sailplane landing procedure is final approach. Besides the sideslipping flight possibility, where energy is dissipated through the increased sideforce drag, another solution for this problem has been offered in literature, showing that the landing distance could be minimized using rather complex oscillating flight paths. The problem is that performing such paths in practice would require exceptional piloting skills. Instead of that, in this paper much simpler approach profiles have been analyzed, based on the simple harmonic speed variations, which could much easier be reproduced in practice. After establishing a quick convergence algorithm, numerical solutions for several typical cases, taking the Vuk-T sailplane as an example, have been presented. Although distance reductions are generally smaller than obtained by distance-minimizing techniques, their operational simplicity and higher safety prove them as valuable solutions for this kind of problems.",
publisher = "Univerzitet u Beogradu - Mašinski fakultet, Beograd",
journal = "FME Transactions",
title = "Uticaj prostih harmonijskih promena brzine ha oblik i dužinu prilazne putanje jedrilice Vuk-T, Influence of simple harmonic speed variations on the Vuk-T sailplane approach paths and distances",
pages = "75-69",
number = "2",
volume = "35",
url = "https://hdl.handle.net/21.15107/rcub_machinery_722"
}

Stefanović, Z.,& Kostić, I.. (2007). Uticaj prostih harmonijskih promena brzine ha oblik i dužinu prilazne putanje jedrilice Vuk-T. in FME Transactions
Univerzitet u Beogradu - Mašinski fakultet, Beograd., 35(2), 69-75.
https://hdl.handle.net/21.15107/rcub_machinery_722

Stefanović Z, Kostić I. Uticaj prostih harmonijskih promena brzine ha oblik i dužinu prilazne putanje jedrilice Vuk-T. in FME Transactions. 2007;35(2):69-75.
https://hdl.handle.net/21.15107/rcub_machinery_722 .

Stefanović, Zoran, Kostić, Ivan, "Uticaj prostih harmonijskih promena brzine ha oblik i dužinu prilazne putanje jedrilice Vuk-T" in FME Transactions, 35, no. 2 (2007):69-75,
https://hdl.handle.net/21.15107/rcub_machinery_722 .