TY  - JOUR
AU  - Ilić, Dejan
AU  - Čantrak, Đorđe
AU  - Janković, Novica
PY  - 2018
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2821
AB  - The results of the experimental investigations of the turbulent swirl flow in a straight conical diffuser with inlet diameter 0.4 m and total divergence angle 8.6 degrees are presented in this paper. The incompressible swirl flow field is generated by the axial fan with outer diameter 0.397 m. The measurements were performed in one measuring section downstream the axial fan impeller in the conical diffuser in position (z/R-0 = 1) with original classical probes and an one-component laser Doppler anemometry (LDA) system, for four flow regimes. The comparative measurements of axial and circumferential velocities are presented. The Reynolds number, calculated on the basis of the average velocity, ranges from 149857 to 216916. Integral parameters, such as volume flow rate, average circulation and swirl number, are determined. Statistical characteristics, such as level of turbulence, skewness and flatness factors, are calculated. The highest levels of turbulence for axial velocity are reached in region 0.4  lt  r/R  lt  0.6, where D = 2R. The highest levels of turbulence for circumferential velocity are reached for the regimes with lower circulation in r/R approximate to 0.4, i.e., in the vortex core region for the cases with higher circulation.
PB  - Srpsko društvo za mehaniku, Beograd
T2  - Theoretical and Applied Mechanics
T1  - INTEGRAL AND STATISTICAL CHARACTERISTICS OF THE TURBULENT SWIRL FLOW IN A STRAIGHT CONICAL DIFFUSER
EP  - 137
IS  - 2
SP  - 127
VL  - 45
DO  - 10.2298/TAM171201012I
ER  - 

@article{
author = "Ilić, Dejan and Čantrak, Đorđe and Janković, Novica",
year = "2018",
abstract = "The results of the experimental investigations of the turbulent swirl flow in a straight conical diffuser with inlet diameter 0.4 m and total divergence angle 8.6 degrees are presented in this paper. The incompressible swirl flow field is generated by the axial fan with outer diameter 0.397 m. The measurements were performed in one measuring section downstream the axial fan impeller in the conical diffuser in position (z/R-0 = 1) with original classical probes and an one-component laser Doppler anemometry (LDA) system, for four flow regimes. The comparative measurements of axial and circumferential velocities are presented. The Reynolds number, calculated on the basis of the average velocity, ranges from 149857 to 216916. Integral parameters, such as volume flow rate, average circulation and swirl number, are determined. Statistical characteristics, such as level of turbulence, skewness and flatness factors, are calculated. The highest levels of turbulence for axial velocity are reached in region 0.4  lt  r/R  lt  0.6, where D = 2R. The highest levels of turbulence for circumferential velocity are reached for the regimes with lower circulation in r/R approximate to 0.4, i.e., in the vortex core region for the cases with higher circulation.",
publisher = "Srpsko društvo za mehaniku, Beograd",
journal = "Theoretical and Applied Mechanics",
title = "INTEGRAL AND STATISTICAL CHARACTERISTICS OF THE TURBULENT SWIRL FLOW IN A STRAIGHT CONICAL DIFFUSER",
pages = "137-127",
number = "2",
volume = "45",
doi = "10.2298/TAM171201012I"
}

Ilić, D., Čantrak, Đ.,& Janković, N.. (2018). INTEGRAL AND STATISTICAL CHARACTERISTICS OF THE TURBULENT SWIRL FLOW IN A STRAIGHT CONICAL DIFFUSER. in Theoretical and Applied Mechanics
Srpsko društvo za mehaniku, Beograd., 45(2), 127-137.
https://doi.org/10.2298/TAM171201012I

Ilić D, Čantrak Đ, Janković N. INTEGRAL AND STATISTICAL CHARACTERISTICS OF THE TURBULENT SWIRL FLOW IN A STRAIGHT CONICAL DIFFUSER. in Theoretical and Applied Mechanics. 2018;45(2):127-137.
doi:10.2298/TAM171201012I .

Ilić, Dejan, Čantrak, Đorđe, Janković, Novica, "INTEGRAL AND STATISTICAL CHARACTERISTICS OF THE TURBULENT SWIRL FLOW IN A STRAIGHT CONICAL DIFFUSER" in Theoretical and Applied Mechanics, 45, no. 2 (2018):127-137,
https://doi.org/10.2298/TAM171201012I . .

TY  - JOUR
AU  - Sekularac, Milan
AU  - Janković, Novica
PY  - 2018
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2861
AB  - To investigate air flow in longitudinally ventilated traffic tunnels, a scaled model of a typical road-traffic tunnel with an appropriate ventilation system based on axial ducted fans, is designed and built in the Lab. The focus of this paper is the airflow in a bi-directional traffic, two-lane tunnel. At the scale ratio of approx. 1:20, at 20.52 m length it represents approximate to 400 m of a real-scale tunnel. The model consists of two parallel tunnel tubes, where the main tunnel (with a hydraulic diameter of D-h1 approximate to 0.4 m has the geometry of a scaled road traffic-tunnel. The second tunnel (D-h2 approximate to 0.16 m) has a smaller size and is circular in cross-section, used only to simulate airflow towards an evacuation tunnel tube. Thus the two tunnels are connected by the evacuation passages, equipped with adjustable escape doors. By a combination of experimental and numerical work, the air flow-field and the performance of the ventilation system are investigated. The velocity field and its turbulence properties exiting the fans were determined experimentally using hot-wire anemometry. These data were further processed to be used in the tunnel flow computations by CFD. The efficiency of momentum transfer (eta(i), Kempf factor) of the longitudinal tunnel ventilation is determined. The effect that the imposed boundary conditions and the level of their detail, have within a CFD computation of tunnel airflow, with respect to accuracy, velocity distribution and computed eta(i), Finally a traffic-loaded (traffic "jam'') case of flow is studied through experiment and CFD. The difficulty in assessing the required thrust of the plant in traffic-jam tunnel conditions is discussed, and the ventilation efficiency is estimated. Based on later results, the two limiting shapes of axial velocity distribution with respect to height above the road, in this type of tunnel and traffic, are estimated. The last result can be used as a realistic boundary condition (as inlet b.c. and/or initial condition) for numerical studies of flow and fire scenarios in such tunnels with the traffic load critical for design.
PB  - Srpsko društvo za mehaniku, Beograd
T2  - Theoretical and Applied Mechanics
T1  - Experimental and numerical analysis of flow field and ventilation performance in a traffic tunnel ventilated by axial fans
EP  - 165
IS  - 2
SP  - 151
VL  - 45
DO  - 10.2298/TAM171201010S
ER  - 

@article{
author = "Sekularac, Milan and Janković, Novica",
year = "2018",
abstract = "To investigate air flow in longitudinally ventilated traffic tunnels, a scaled model of a typical road-traffic tunnel with an appropriate ventilation system based on axial ducted fans, is designed and built in the Lab. The focus of this paper is the airflow in a bi-directional traffic, two-lane tunnel. At the scale ratio of approx. 1:20, at 20.52 m length it represents approximate to 400 m of a real-scale tunnel. The model consists of two parallel tunnel tubes, where the main tunnel (with a hydraulic diameter of D-h1 approximate to 0.4 m has the geometry of a scaled road traffic-tunnel. The second tunnel (D-h2 approximate to 0.16 m) has a smaller size and is circular in cross-section, used only to simulate airflow towards an evacuation tunnel tube. Thus the two tunnels are connected by the evacuation passages, equipped with adjustable escape doors. By a combination of experimental and numerical work, the air flow-field and the performance of the ventilation system are investigated. The velocity field and its turbulence properties exiting the fans were determined experimentally using hot-wire anemometry. These data were further processed to be used in the tunnel flow computations by CFD. The efficiency of momentum transfer (eta(i), Kempf factor) of the longitudinal tunnel ventilation is determined. The effect that the imposed boundary conditions and the level of their detail, have within a CFD computation of tunnel airflow, with respect to accuracy, velocity distribution and computed eta(i), Finally a traffic-loaded (traffic "jam'') case of flow is studied through experiment and CFD. The difficulty in assessing the required thrust of the plant in traffic-jam tunnel conditions is discussed, and the ventilation efficiency is estimated. Based on later results, the two limiting shapes of axial velocity distribution with respect to height above the road, in this type of tunnel and traffic, are estimated. The last result can be used as a realistic boundary condition (as inlet b.c. and/or initial condition) for numerical studies of flow and fire scenarios in such tunnels with the traffic load critical for design.",
publisher = "Srpsko društvo za mehaniku, Beograd",
journal = "Theoretical and Applied Mechanics",
title = "Experimental and numerical analysis of flow field and ventilation performance in a traffic tunnel ventilated by axial fans",
pages = "165-151",
number = "2",
volume = "45",
doi = "10.2298/TAM171201010S"
}

Sekularac, M.,& Janković, N.. (2018). Experimental and numerical analysis of flow field and ventilation performance in a traffic tunnel ventilated by axial fans. in Theoretical and Applied Mechanics
Srpsko društvo za mehaniku, Beograd., 45(2), 151-165.
https://doi.org/10.2298/TAM171201010S

Sekularac M, Janković N. Experimental and numerical analysis of flow field and ventilation performance in a traffic tunnel ventilated by axial fans. in Theoretical and Applied Mechanics. 2018;45(2):151-165.
doi:10.2298/TAM171201010S .

Sekularac, Milan, Janković, Novica, "Experimental and numerical analysis of flow field and ventilation performance in a traffic tunnel ventilated by axial fans" in Theoretical and Applied Mechanics, 45, no. 2 (2018):151-165,
https://doi.org/10.2298/TAM171201010S . .