地效环境下悬停状态直升机旋翼桨/涡干扰噪声特性  

Hovering helicopter rotor blade/vortex interaction noise characteristics in ground effect environment

作　　者：王伟琪 陈希[1] 招启军[1] WANG Weiqi;CHEN Xi;ZHAO Qijun(National Key Laboratory of Helicopter Aeromechanics,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China)

机构地区：[1]南京航空航天大学直升机动力学全国重点实验室,南京210016

出　　处：《航空学报》2024年第12期67-81,共15页Acta Aeronautica et Astronautica Sinica

基　　金：国家自然科学基金(12032012);江苏高校优势学科建设工程资助项目。

摘　　要：为掌握直升机贴地飞行时旋翼噪声辐射特性,首先基于可压缩雷诺平均Navier-Stokes方程和Ffowcs Williams-Hawkings方程发展了一套适用于地效状态旋翼/机身干扰的气动与噪声分析方法,通过Lynx尾桨地面效应试验及NASA旋翼/机身干扰试验与计算结果的对比,验证了所建立方法的可靠性。然后,开展了机身和桨毂对旋翼流场的影响研究,发现机身改变了旋翼的气动载荷分布并提高中等阶次(8~12阶次)的噪声辐射水平;桨毂会削弱桨叶中段(r=0.4R~0.7R,R为旋翼半径)的噪声贡献。最后,研究了不同离地高度(h)时旋翼的气动与噪声特性,发现存在一个出现桨/涡干扰噪声的“临界离地高度”。结果表明:旋翼拉力和机身升力随h增大而减小;当h>1.8R时地面效应的影响可以忽略;当h=0.6R时地面和机身的双重阻塞作用会改变旋翼入流情况,尤其在桨尖区域诱发剧烈的载荷波动,并在特征观测点接收到明显的桨/涡干扰噪声;根据时/频特性给出了本文的“临界离地高度”约为0.7R,为直升机贴地飞行时抑制噪声提供了参考。To grasp rotor aeroacoustic radiation characteristics during helicopter flight close to the ground,firstly,based on the compressible Reynolds average Navier-Stokes equations and the Ffowcs Williams-Hawkings equations,a set of aerodynamic and aeroacoustic analysis method suitable for rotor/fuselage interaction in ground effect state was developed.The reliability of the established method was verified by comparing the ground effect test of Lynx tail rotor and the NASA rotor/fuselage interaction test with calculation results.Then,the influence of fuselage and hub on the rotor flowfield was investigated.It was found that the fuselage could change the rotor aerodynamic load distribution and increase the aeroacoustic radiation level of the intermediate order(8th-12th order).The aeroacoustic contribution of the blade middle section(r=0.4R-0.7R,R is the radius of rotor)could be weaken by the hub.Finally,the aerody-namic and aeroacoustic characteristics of the rotor at different heights(h)above the ground were investigated and a"critical ground height"with BladeNVortex Interaction(BVl)noise was found.The results show that the rotor thrust and fuselage lift decrease with the increase of ground height.When h>1.8R,the influence of ground effect can be ig-nored.When h=0.6R,the inflow of the rotor will be changed by the blocking effect of the ground and the fuselage.Especially,load fluctuations are induced severely in the blade tip area and obvious BVl noise is received at the charac-teristic observation points.According to the time/frequency characteristics,this paper suggests a"critical ground height"of approximately O.7R,which provides a reference for the noise suppression when the helicopter flies close to the ground.

关 键 词：旋翼气动噪声 FW-H方程 旋翼/机身干扰 地面效应 桨/涡干扰噪声 

分 类 号：V211.52[航空宇航科学与技术—航空宇航推进理论与工程]