한국항공우주학회지 (Journal of the Korean Society for Aeronautical & Space Sciences)

  • 제50권9호
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  • Pages.599-608
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  • 2022
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  • 1225-1348(pISSN)
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  • 2287-6871(eISSN)
한국항공우주학회 (The Korean Society for Aeronautical and Space Sciences)
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동축 반전 전기동력 수직이착륙기의 지면 효과에 대한 전산해석

Computational Simulation of Coaxial eVTOL Aircraft in Ground Effect

  • Yang, Jin-Yong (School of Mechanical and Aerospace Engineering, Gyeongsang National University) ;
  • Lee, Hyeok-Jin (School of Mechanical and Aerospace Engineering, Gyeongsang National University) ;
  • Myong, Rho-Shin (School of Mechanical and Aerospace Engineering, Gyeongsang National University) ;
  • Lee, Hakjin (School of Mechanical and Aerospace Engineering, Gyeongsang National University)
  • 투고 : 2022.05.04
  • 심사 : 2022.07.18
  • 발행 : 2022.09.01
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초록

로터 시스템을 사용하는 도심 항공 모빌리티(Urban Air Mobility, UAM)는 이착륙 시 버티포트(Vertiport)에서 지면 효과를 경험하게 된다. UAM의 안전한 운용을 위해서는 지면 효과가 비행체의 공력성능에 미치는 영향성이 선행적으로 분석되어야 한다. 본 연구에서는 Lattice Boltzmann Method (LBM)를 적용하여지면 효과가 동축 반전 프로펠러를 장착한 쿼드콥터 형상 전기동력 수직이착륙기 전기체의 공력성능 및 후류 구조에 미치는 영향을 분석하였다. 동축 반전 프로펠러 시스템의 상하부 프로펠러에서 지면 효과 영향성은 상이하게 관찰되었다. 지면과의 이격 거리가 변화하더라도 상부 프로펠러의 성능에는 큰 변화가 없었지만, 지면과 가까워질수록 하부 프로펠러에서는 평균 추력과 토크 값이 크게 증가하였다. 또한 이격 거리가 감소함에 따라 추력 변동의 진폭이 증가하는 경향성이 나타났다. 지면 효과에 의해 프로펠러 후류는 하류 방향으로 충분히 전파되지 못하고 지면을 따라 발달한 Outwash 흐름에 의해 확산되었다. 프로펠러 시스템 사이에서 지면 확산 유동이 충돌하는 분수 와류(Fountain Vortex)의 형성을 확인하였다.

Urban air mobility (UAM) equipped with rotor system is subject to ground effect at vertiport during takeoff and landing. The aerodynamic performance of the aircraft in ground effect should be analyzed for the safe operation. In this study, The ground effects on the aerodynamic performance and wake structure of the quadcopter electric vertical takeoff and landing (eVTOL) configuration equipped with coaxial counter-rotating propellers were investigated by using the lattice Boltzmann method (LBM). The influence of the ground effect was observed differently in the upper and lower propellers of the coaxial counter-rotating propeller system. There was no significant change in the aerodynamic performance of the upper propeller even if the propeller height above the ground was changed, whereas the averaged thrust and torque of the lower propeller increased significantly as propeller height decreased. In addition, the amplitude of the thrust fluctuation tended to increase as the propeller height decreased. The propeller wake was not sufficiently propagated downstream and was diffused along the ground due to the outwash flow developed by the ground effect. The impingement of the rotor wakes on the ground and a fountain vortex structure were observed.

키워드

과제정보

본 연구는 과학기술정보통신부의 재원으로 한국연구재단의 지원을 받아 수행되었습니다. (NRF-2017R1A5A1015311, NRF-2021R1C1C1010198)

참고문헌

  1. UBER elevate, Fast-Forwarding to a Future of On-Demand Urban Air Transportation, 2016.
  2. Jun, Y., Oh, K., Lee, J. and Chung, K. H., "Urban Air Mobility Trend," Current Industrial and Technological Trends in Aerospace, Vol. 18, No. 1, 2020, pp. 37~48.
  3. Leishman, G. J., Principles of Helicopter Aerodynamics, 2nd Ed., Cambridge University Press, NewYork, 2006.
  4. Lee, T. E., Leishman, J. G. and Ramasamy, M., "Fluid Dynamics of Interacting Blade Tip Vortices with a Ground Plane," Journal of the American Helicopter Society, Vol. 55, No. 2, 2010, pp. 22005-1~16.
  5. Light, J. S., "Tip Vortex Geometry of a Hovering Helicopter Rotor in Ground Effect," Journal of the American Helicopter Society, Vol. 38, No. 2, 1993, pp. 34~42. https://doi.org/10.4050/JAHS.38.34
  6. Curtiss, H. C., Sun, M., Putman, W. F. and Hanker, E. J., "Rotor Aerodynamics in Ground Effect at Low Advance Ratios," Journal of the American Helicopter Society, Vol. 29, No. 1, 1984, pp. 48~55. https://doi.org/10.4050/JAHS.29.48
  7. Kalra, T. S., Lakshminarayan, V. K., Baeder, J. D. and Thomas, S., "Methodological Improvements for Computational Study of Hovering Micro-Rotor in Ground Effect," AIAA Paper 11-3552.
  8. Lakshminarayan, V. K., Kalra, T. S. and Baeder, J. D., "Detailed Computational Investigation of a Hovering Microscale Rotor in Ground Effect," AIAA Journal, Vol. 51, No. 4, 2013, pp. 893~909. https://doi.org/10.2514/1.J051789
  9. Hwang, J. Y. and Kwon, O. J., "Assessment of S-76 Rotor Hover Performance in Ground Effect Using an Unstructured Mixed Mesh Method," Aerospace Science and Technology, Vol. 84, 2019, pp. 223~236. https://doi.org/10.1016/j.ast.2018.10.023
  10. Griffiths, D. A., Ananthan, S. and Leishman, J. G., "Predictions of Rotor Performance in Ground Effect using a Free-Vortex Wake Model," Journal of the American Helicopter Society, Vol. 50, No. 4, 2005, pp. 302~314. https://doi.org/10.4050/1.3092867
  11. Phillips, C. and Brown, R. E., "Eulerian Simulation of the Fluid Dynamics of Helicopter Brownout," Journal of Aircraft, Vol. 46, No. 4, 2009, pp. 1416~1429. https://doi.org/10.2514/1.41999
  12. Phillips, C. and Brown, R. E., "The Effect of Helicopter Configuration on the Fluid Dynamics of Brownout," Proceedings of the 34th European Rotorcraft Forum, September 2008, pp. 2398~2426.
  13. Zhao, J. and He, C., "Physics-Based Modeling of Viscous Ground Effect for Rotorcraft Applications," Journal of the American Helicopter Society, Vol. 60, No. 3, 2015, pp. 1~13. https://doi.org/10.4050/JAHS.60.032006
  14. Tan, J. F., Gao, J., Barakos, G. N., Lin, C. L., Zhang, W. G. and Huang, M. Q., "Novel Approach to Helicopter Brownout Based on Vortex and Discrete Element Methods," Aerospace Science and Technology, Vol. 116, 2021, pp. 106839-1~15.
  15. Srinivasan, G. R., Baeder, J. D., Obayashi, S. and McCroskey, W. J., "Flowfield of a Lifting Rotor in Hover: A Navier-Stokes Simulation," AIAA Journal, Vol. 30, No. 10, 1992, pp. 2371~2378. https://doi.org/10.2514/3.11236
  16. Kang, H. J. and Kwon, O. J., "Unstructured Mesh Navier-Stokes Calculations of the Flow Field of a Helicopter Rotor in Hover," Journal of the American Helicopter Society, Vol. 47, No. 2, 2002, pp. 90~99. https://doi.org/10.4050/JAHS.47.90
  17. Park, S., Lee, J., Lee, S., Yee, K. and Oh, S., "Development and Validations of the Aerodynamic Analysis Program of Multi-Rotors by using a Free-Wake Method," Journal of the Korean Society for Aeronautical and Space Sciences, Vol. 35, No. 10, 2007, pp. 859~867. https://doi.org/10.5139/JKSAS.2007.35.10.859
  18. Wie, S. Y. and Lee, D. J., "An Analysis of BVI Unsteady Rotor Aerodynamics using Unsteady Panel and Time-Marching Free Wake," Journal of the Korean Society for Aeronautical and Space Sciences, Vol. 37, No. 4, 2009, pp. 329~335. https://doi.org/10.5139/JKSAS.2009.37.4.329
  19. Lee, H. J., Yang, J. Y., Myong, R. S. and Lee, H., "Aerodynamic Analysis of Rotor Blade in Hovering and Forward Flight Using Lattice-Boltzmann Method," Journal of Computational Fluids Engineering, Vol. 26, No. 4, 2021, pp. 115~124. https://doi.org/10.6112/kscfe.2021.26.4.115
  20. Thurman, C. S., Zawodny, N. S., Pettingill, N. A., Lopes, L. V. and Baeder, J. D., "Physics-Informed Broadband Noise Source Identification and Prediction of an Ideally Twisted Rotor," AIAA Paper 21-1925.
  21. Romani, G. and Casalino, D., "Rotorcraft Blade-Vortex Interaction Noise Prediction using the Lattice-Boltzmann Method," Aerospace Science and Technology, Vol. 88, 2019, pp. 147~157. https://doi.org/10.1016/j.ast.2019.03.029
  22. Casalino, D., van der Velden, W. C. P. and Romani, G., "Community Noise of Urban Air Transportation Vehicles," AIAA Paper 19-1834.
  23. Bludau, J., Rauleder, J., Friedmann, L. and Hajek, M., "Real-Time Simulation of Dynamic Inflow using Rotorcraft Flight Dynamics Coupled with a Lattice-Boltzmann based Fluid Simulation," AIAA Paper 17-0050.
  24. Gourdain, N., Singh, D., Jardin, T. and Prothin, S., "Analysis of the Turbulent Wake Generated by a Micro Air Vehicle Hovering near the Ground with a Lattice Boltzmann Method," Journal of the American Helicopter Society, Vol. 62, No. 4, 2017, pp. 1~12.
  25. Gourdain, N., Jardin, T., Serre, R., Prothin, S. and Moschetta, J. M., "Application of a Lattice Boltzmann Method to Some Challenges Related to Micro-Air Vehicles," International Journal of Micro Air Vehicles, Vol. 10, No. 3, pp. 285~299.
  26. Kutay, M. E., Aydilek, A. H. and Masad, E., "Laboratory Validation of Lattice Boltzmann Method for Modeling Pore-Scale Flow in Granular Materials," Computers and Geotechnics, Vol. 33, No. 8, 2006, pp. 381~395. https://doi.org/10.1016/j.compgeo.2006.08.002
  27. Kotapati, R. B., Shock, R. and Chen, H., "Lattice-Boltzmann Simulations of Flows over Backward-Facing Inclined Steps," International Journal of Modern Physics C, Vol. 25, No. 1, 2014, pp. 1340021-1~14.
  28. Bhatnagar, P. L., Gross, E. P. and Krook, M., "A Model for Collision Processes in Gases. I. Small Amplitude Processes in Charged and Neutral One-Component Systems," Physical Review, Vol. 94, No. 3, 1954, pp. 511~525. https://doi.org/10.1103/PhysRev.94.511
  29. Yakhod, V. and Orszag, S. A., "Renormalization Group Analysis of Turbulence. I. Basic Theory," Journal of Scientific Computing, Vol. 1, No. 1, 1986, pp. 3~51. https://doi.org/10.1007/BF01061452
  30. Teixeira, C. M., "Incoporating Turbulence Models into the Lattice-Boltzmann Method," International Journal of Modern Physics C, Vol. 9, No. 8, 1998, pp. 1159~1175. https://doi.org/10.1142/S0129183198001060
  31. Chen, H., Kandasamy, S., Orszag, S., Shock, R., Succi, S. and Yakhot, V., "Extended Boltzmann Kinetic Equation for Turbulent Flows," Science, Vol. 301, No. 5633, 2003, pp. 633~636. https://doi.org/10.1126/science.1085048
  32. Caradonna, F. X. and Tung, C., "Experimental and Analytical Studies of a Model Helicopter Rotor in Hover," NASA TM-81232, 1981.
  33. Sim, M. C., Lee, K. T. and Kim, H. D., "Numerical Investigation of the Effect of Spacing in Coaxial Propeller Multi-Copter in Hovering," Journal of the Korean Society for Aeronautical and Space Sciences, Vol. 48, No. 2, 2020, pp. 89~97.
  34. Ramasamy, M., "Hover Performance Measurements Toward Understanding Aerodynamic Interference in Coaxial, Tandem, and Tilt Rotors," Journal of the American Helicopter Society, Vol. 60, No. 3, 2015, pp. 1~17. https://doi.org/10.4050/JAHS.60.032005