反流及径向流动相互作用下刚性旋翼气动特性研究
|
摘要
采用雷诺平均(Reynolds-averaged Navier-Stokes,RANS)方程针对直升机前飞不同前进比状态下四叶片刚性旋翼开展数值模拟研究,对比前进比0.1和0.6时的旋翼气动特性差异。计算结果表明,前飞时桨盘后行侧根部附近出现反流流动区域,翼型截面压强系数呈现非常规分布,该区域桨叶几乎不提供升力,且反流区面积随前进比的增大而增加。以静态前掠反流翼段为研究对象,采用脱体涡(Detached eddy simulation,DES)方法研究其非定常空气动力学特性,发现反流翼段表面出现特殊复杂的附着涡结构,在展向流动的影响下,翼段根部与尖部的涡结构发生耦合作用;反流翼段的升力系数随桨距角的增加而增大,且在失速迎角后并未下降。
The aerodynamic characteristics of a rigid four-bladed rotor in forward flight at advance ratio of 0.1 and 0.6 are simulated numerically with Reynolds-averaged Navier-Stokes(RANS)methods and compared with each other. The computed results indicate that reverse flow occurs near the root area of the retreating side of the rotor,giving rise to the unconventional distributions of pressure coefficient. And the proportion of the reverse flow region,where hardly any lift is contributed,is directly related to the advance ratio and increases with the raise of the advance ratio. Detached eddy simulation(DES)method is used to calculate the unsteady aerodynamic characteristics of a yawed flat blade in reverse flow. It is found that complex attached vortex structure occurs on the surface of the blade and the vortex near the root interacts with that near the tip area under the effect of the radial flow. The lift coefficient is directly proportional to the pitch angle and does not drop after the stall angle of attack.
The aerodynamic characteristics of a rigid four-bladed rotor in forward flight at advance ratio of 0.1 and 0.6 are simulated numerically with Reynolds-averaged Navier-Stokes(RANS)methods and compared with each other. The computed results indicate that reverse flow occurs near the root area of the retreating side of the rotor,giving rise to the unconventional distributions of pressure coefficient. And the proportion of the reverse flow region,where hardly any lift is contributed,is directly related to the advance ratio and increases with the raise of the advance ratio. Detached eddy simulation(DES)method is used to calculate the unsteady aerodynamic characteristics of a yawed flat blade in reverse flow. It is found that complex attached vortex structure occurs on the surface of the blade and the vortex near the root interacts with that near the tip area under the effect of the radial flow. The lift coefficient is directly proportional to the pitch angle and does not drop after the stall angle of attack.
引文
[1]YEO H,JOHNSON W.Aeromechanics analysis of a compound helicopter[C]//Annual Forum ProceedingsAHS International.[S.l.]:AHS,2006.
[2]STEIJL R,BARAKOS G,BADCOCK K.Aframework for CFD analysis of helicopter rotors in hover and forward flight[J].International Journal for Numerical Methods in Fluids,2006,51(8):819-847.
[3]LIND A H,LEFEBVRE J N,JONES A R.Experimental investigation of reverse flow over sharp and blunt trailing edge airfoils[C]//31st AIAA Applied Aerodynamics Conference.San Diego,CA:AIAA,2013.
[4]LIND A H,LEFEBVRE J N,JONES A R.Timeaveraged aerodynamics of sharp and blunt trailing-edge static airfoils in reverse flow[J].American Institute of Aeronautics and Astronautics Journal,2015,52(12):1-18.
[5]LIND A H,JONES A R.Vortex shedding from airfoils in reverse flow[J].American Institute of Aeronautics and Astronautics Journal,2015,53(9):1-13.
[6]LIND A H,SMITH L R,MILLUZZO J,et al.Reynolds number effects on airfoils in reverse flow[C]//53rd AIAA Aerospace Sciences Meeting.Kissimmee,Florida:AIAA,2013.
[7]LIND A H,SMITH L R,MILLUZZO J I,et al.Reynolds number effects on rotor blade sections in reverse flow[J].Journal of Aircraft,2016,53(5):1248-1260.
[8]RAGHAV V,MAYO M,LOZANO R,et al.Evidence of vortex-induced lift on a yawed wing in reverse flow[J].Proceedings of the Institution of Mechanical Engineers,Part G:Journal of Aerospace Engineering,2014,228(11):2130-2137.
[9]MAYO M,RAGHAV V,KOMERATH N.Vortex flow hypothesis for a yawed rotor blade in reverse flow[J].Proceedings of the Institution of Mechanical Engineers,Part G:Journal of Aerospace Engineering,2015,229(3):543-553.
[10]RAGHAV V,KOMERATH N.An exploration of radial flow on a rotating blade in retreating blade stall[J].Journal of the American Helicopter Society,2013,58(2):1-10.
[11]RAGHAV V,KOMERATH N.The intricacies of measuring radial velocity field on a rotating disk with edgewise flow[C]//50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition.Nashville,Tennessee:AIAA,2012:424.
[12]YEO H.Investigation of UH-60A rotor performance and loads at high advance ratios[J].Journal of Aircraft,2013,50(2):576-589.
[13]POTSDAM M,DATTA A,JAYARAMAN B.Computational investigation and fundamental understanding of a slowed UH-60A rotor at high advance ratios[J].Journal of the American Helicopter Society,2016,4(4):1-14.
[14]袁明川,杨永飞,林永峰.高速直升机旋翼反流区桨叶剖面翼型气动特性CFD分析[J].直升机技术,2015(1):1-5.YUAN Mingchuan,YANG Yongfei,LIN Yongfeng.CFD analysis on aerodynamic characteristics of blade profiles in reverse flow region of high speed helicopter rotor[J].Helicopter Technique,2015(1):1-5.
[15]CARADONNA F X,TUNG C.Experimental and analytical studies of a model helicopter rotor in hover[R].NASA-TM-81232,1981.
[2]STEIJL R,BARAKOS G,BADCOCK K.Aframework for CFD analysis of helicopter rotors in hover and forward flight[J].International Journal for Numerical Methods in Fluids,2006,51(8):819-847.
[3]LIND A H,LEFEBVRE J N,JONES A R.Experimental investigation of reverse flow over sharp and blunt trailing edge airfoils[C]//31st AIAA Applied Aerodynamics Conference.San Diego,CA:AIAA,2013.
[4]LIND A H,LEFEBVRE J N,JONES A R.Timeaveraged aerodynamics of sharp and blunt trailing-edge static airfoils in reverse flow[J].American Institute of Aeronautics and Astronautics Journal,2015,52(12):1-18.
[5]LIND A H,JONES A R.Vortex shedding from airfoils in reverse flow[J].American Institute of Aeronautics and Astronautics Journal,2015,53(9):1-13.
[6]LIND A H,SMITH L R,MILLUZZO J,et al.Reynolds number effects on airfoils in reverse flow[C]//53rd AIAA Aerospace Sciences Meeting.Kissimmee,Florida:AIAA,2013.
[7]LIND A H,SMITH L R,MILLUZZO J I,et al.Reynolds number effects on rotor blade sections in reverse flow[J].Journal of Aircraft,2016,53(5):1248-1260.
[8]RAGHAV V,MAYO M,LOZANO R,et al.Evidence of vortex-induced lift on a yawed wing in reverse flow[J].Proceedings of the Institution of Mechanical Engineers,Part G:Journal of Aerospace Engineering,2014,228(11):2130-2137.
[9]MAYO M,RAGHAV V,KOMERATH N.Vortex flow hypothesis for a yawed rotor blade in reverse flow[J].Proceedings of the Institution of Mechanical Engineers,Part G:Journal of Aerospace Engineering,2015,229(3):543-553.
[10]RAGHAV V,KOMERATH N.An exploration of radial flow on a rotating blade in retreating blade stall[J].Journal of the American Helicopter Society,2013,58(2):1-10.
[11]RAGHAV V,KOMERATH N.The intricacies of measuring radial velocity field on a rotating disk with edgewise flow[C]//50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition.Nashville,Tennessee:AIAA,2012:424.
[12]YEO H.Investigation of UH-60A rotor performance and loads at high advance ratios[J].Journal of Aircraft,2013,50(2):576-589.
[13]POTSDAM M,DATTA A,JAYARAMAN B.Computational investigation and fundamental understanding of a slowed UH-60A rotor at high advance ratios[J].Journal of the American Helicopter Society,2016,4(4):1-14.
[14]袁明川,杨永飞,林永峰.高速直升机旋翼反流区桨叶剖面翼型气动特性CFD分析[J].直升机技术,2015(1):1-5.YUAN Mingchuan,YANG Yongfei,LIN Yongfeng.CFD analysis on aerodynamic characteristics of blade profiles in reverse flow region of high speed helicopter rotor[J].Helicopter Technique,2015(1):1-5.
[15]CARADONNA F X,TUNG C.Experimental and analytical studies of a model helicopter rotor in hover[R].NASA-TM-81232,1981.