Challenges to accurate computation of propeller performances at low angular velocities
Само за регистроване кориснике
2021
Конференцијски прилог (Објављена верзија)
Метаподаци
Приказ свих података о документуАпстракт
The main topic of the presented study is the alteration (i.e. possible degradation) of aerodynamic performances of small-scale rotors (applicable to today so popular unmanned multi-rotor air vehicles) at particularly low angular velocities (corresponding to 15-30% throttle that also imply low Reynolds number flows), i.e. particularly off-design operating conditions. These ranges of working regimes have not been investigated much (although they incorporate various interesting flow phenomena) and available data for validation is scarce, even though small-scale multi-rotor aircrafts usually carry rotors of fixed geometry and are controlled solely by changing the rotor angular velocities (that in turn produces changes in generated forces and moments).
Although flows around rotor blades (at off-design conditions) are predominantly turbulent, other, much simpler and computationally less expensive numerical methods, such as blade element momentum theory (BEMT), are still used today for a qui...ck estimation of propeller thrust and torque (i.e. power). By comparing the results obtained by different computational models, it is possible to evaluate their applicability and accuracy. Here, in order to quantify the changes in propeller flow behavior, both hover and axisymmetric flight condition were numerically investigated by two computational methods differing in complexity − BEMT vs. (U)RANS, and compared against the available experimental data.
The paper briefly describes both employed numerical models and accentuates differences between them. Furthermore, in hover, quasi-steady RANS approach (by multiple reference frames) is compared to the URANS realized by sliding meshes. In both cases, the flow equations are closed by the well-proven and much employed k-ω SST turbulence model. Presented results include thrust and torque curves, as well as different flow visualizations. In the end, given that rotor characteristics may have dramatic effects on overall aircraft performance, it can be concluded that the accurate estimation of rotor thrust and torque at low angular velocities is extremely important but also quite hard to make. The differences between experimental and numerical data can amount to 50%, while degradation of rotor performances in flight at low Re can reach 20%.
Кључне речи:
propeller / BEMT / flow computation / off-design conditions / turbulenceИзвор:
Proceedings / The 8th International Congress of Serbian Society of Mechanics, Kragujevac, Serbia, June 28-30, 2021, 2021, 568-577Издавач:
- Belgrade : Serbian Society of Mechanics
Финансирање / пројекти:
- Министарство науке, технолошког развоја и иновација Републике Србије, институционално финансирање - 200105 (Универзитет у Београду, Машински факултет) (RS-MESTD-inst-2020-200105)
Колекције
Институција/група
Mašinski fakultetTY - CONF AU - Svorcan, Jelena PY - 2021 UR - https://machinery.mas.bg.ac.rs/handle/123456789/4214 AB - The main topic of the presented study is the alteration (i.e. possible degradation) of aerodynamic performances of small-scale rotors (applicable to today so popular unmanned multi-rotor air vehicles) at particularly low angular velocities (corresponding to 15-30% throttle that also imply low Reynolds number flows), i.e. particularly off-design operating conditions. These ranges of working regimes have not been investigated much (although they incorporate various interesting flow phenomena) and available data for validation is scarce, even though small-scale multi-rotor aircrafts usually carry rotors of fixed geometry and are controlled solely by changing the rotor angular velocities (that in turn produces changes in generated forces and moments). Although flows around rotor blades (at off-design conditions) are predominantly turbulent, other, much simpler and computationally less expensive numerical methods, such as blade element momentum theory (BEMT), are still used today for a quick estimation of propeller thrust and torque (i.e. power). By comparing the results obtained by different computational models, it is possible to evaluate their applicability and accuracy. Here, in order to quantify the changes in propeller flow behavior, both hover and axisymmetric flight condition were numerically investigated by two computational methods differing in complexity − BEMT vs. (U)RANS, and compared against the available experimental data. The paper briefly describes both employed numerical models and accentuates differences between them. Furthermore, in hover, quasi-steady RANS approach (by multiple reference frames) is compared to the URANS realized by sliding meshes. In both cases, the flow equations are closed by the well-proven and much employed k-ω SST turbulence model. Presented results include thrust and torque curves, as well as different flow visualizations. In the end, given that rotor characteristics may have dramatic effects on overall aircraft performance, it can be concluded that the accurate estimation of rotor thrust and torque at low angular velocities is extremely important but also quite hard to make. The differences between experimental and numerical data can amount to 50%, while degradation of rotor performances in flight at low Re can reach 20%. PB - Belgrade : Serbian Society of Mechanics C3 - Proceedings / The 8th International Congress of Serbian Society of Mechanics, Kragujevac, Serbia, June 28-30, 2021 T1 - Challenges to accurate computation of propeller performances at low angular velocities EP - 577 SP - 568 UR - https://hdl.handle.net/21.15107/rcub_machinery_4214 ER -
@conference{ author = "Svorcan, Jelena", year = "2021", abstract = "The main topic of the presented study is the alteration (i.e. possible degradation) of aerodynamic performances of small-scale rotors (applicable to today so popular unmanned multi-rotor air vehicles) at particularly low angular velocities (corresponding to 15-30% throttle that also imply low Reynolds number flows), i.e. particularly off-design operating conditions. These ranges of working regimes have not been investigated much (although they incorporate various interesting flow phenomena) and available data for validation is scarce, even though small-scale multi-rotor aircrafts usually carry rotors of fixed geometry and are controlled solely by changing the rotor angular velocities (that in turn produces changes in generated forces and moments). Although flows around rotor blades (at off-design conditions) are predominantly turbulent, other, much simpler and computationally less expensive numerical methods, such as blade element momentum theory (BEMT), are still used today for a quick estimation of propeller thrust and torque (i.e. power). By comparing the results obtained by different computational models, it is possible to evaluate their applicability and accuracy. Here, in order to quantify the changes in propeller flow behavior, both hover and axisymmetric flight condition were numerically investigated by two computational methods differing in complexity − BEMT vs. (U)RANS, and compared against the available experimental data. The paper briefly describes both employed numerical models and accentuates differences between them. Furthermore, in hover, quasi-steady RANS approach (by multiple reference frames) is compared to the URANS realized by sliding meshes. In both cases, the flow equations are closed by the well-proven and much employed k-ω SST turbulence model. Presented results include thrust and torque curves, as well as different flow visualizations. In the end, given that rotor characteristics may have dramatic effects on overall aircraft performance, it can be concluded that the accurate estimation of rotor thrust and torque at low angular velocities is extremely important but also quite hard to make. The differences between experimental and numerical data can amount to 50%, while degradation of rotor performances in flight at low Re can reach 20%.", publisher = "Belgrade : Serbian Society of Mechanics", journal = "Proceedings / The 8th International Congress of Serbian Society of Mechanics, Kragujevac, Serbia, June 28-30, 2021", title = "Challenges to accurate computation of propeller performances at low angular velocities", pages = "577-568", url = "https://hdl.handle.net/21.15107/rcub_machinery_4214" }
Svorcan, J.. (2021). Challenges to accurate computation of propeller performances at low angular velocities. in Proceedings / The 8th International Congress of Serbian Society of Mechanics, Kragujevac, Serbia, June 28-30, 2021 Belgrade : Serbian Society of Mechanics., 568-577. https://hdl.handle.net/21.15107/rcub_machinery_4214
Svorcan J. Challenges to accurate computation of propeller performances at low angular velocities. in Proceedings / The 8th International Congress of Serbian Society of Mechanics, Kragujevac, Serbia, June 28-30, 2021. 2021;:568-577. https://hdl.handle.net/21.15107/rcub_machinery_4214 .
Svorcan, Jelena, "Challenges to accurate computation of propeller performances at low angular velocities" in Proceedings / The 8th International Congress of Serbian Society of Mechanics, Kragujevac, Serbia, June 28-30, 2021 (2021):568-577, https://hdl.handle.net/21.15107/rcub_machinery_4214 .