直升机旋翼桨-涡干扰噪声是一种严重的脉冲声源，为研究旋翼非定常流动对桨-涡干扰噪声特性影响机理，基于麦克风球面声阵列测量技术、桨叶表面压力测量技术和粒子图像测速（PIV）技术，在声学风洞环境下测量获得了旋翼不同状态下的桨-涡干扰噪声特性、压力分布和非定常流动特性，以及总结了前进比、斜下降角和垂向力系数等旋翼状态参数对桨-涡干扰噪声的影响特性，揭示了旋翼桨叶表面压力、涡运动轨迹对桨-涡干扰噪声的影响机理。分析结果表明：BVI噪声的主要辐射方向覆盖了第一到第三象限的大部分范围，在时域上表现为峰值很高的脉冲声压，且主要声能量频率集中在中高频段的旋转频率的倍频上；桨-涡干扰主要发生在桨叶前缘，一般在0.3倍弦长以内，越靠近前缘干扰越强，且上下翼面干扰载荷的脉冲方向相反；对于5片桨叶旋翼，桨-涡平行干扰的相位约为60°；平行干扰状态下，桨叶展向大部分范围均与涡发生了干扰作用，产生了噪声的集聚效应；旋翼前进比和斜下降角的变化会引起旋翼附近流动的变化，进而改变脱落的桨尖涡的运动轨迹以及桨叶与涡干扰的相对角度、距离和干扰相位，从而影响了旋翼桨-涡干扰噪声；旋翼垂向力系数改变，不会影响桨尖涡的运动轨迹，但会影响旋翼桨尖涡的涡强，进而影响桨-涡干扰噪声的强度。
The blade-vortex interaction noise of helicopter rotor is a severe impulsive noise source. In order to investigate the influence mecha-nism of the unsteady flow of the rotor on the blade-vortex interaction noise characteristics, the noise characteristics, pressure distri-bution, and unsteady flow characteristics of the rotor different conditions are measured based on the microphone spherical array measurement technology, the blade surface pressure measurement technology, and the particle image velocimetry(PIV) technology in an acoustic tunnel environment. The influence characteristics of the advance ratio, oblique descent angle, and lift coefficient on the blade-vortex interaction noise are obtained. The influence mechanism of the rotor surface pressure and the vortex motion trajectory on the blade-vortex interaction noise are revealed. The analysis results show that the main radiation direction of BVI noise covers most of the first to third quadrants. In the time domain, it shows a high peak pulse noise pressure, and the main sound energy fre-quency is concentrated on the multiples of the rotational frequency in the and medium
-high frequency bands. The blade-vortex interaction noise mainly occurs at the blade leading edge, generally within 0.3 times of the chord length, with intensity inversely proportional to the distance. Upper and lower surface interaction loads exhibit opposing impul-sive directions. For 5-bladed rotors, parallel BVI phases approximate 60°. Spanwise cumulative noise effects arise from extensive blade-vortex interactions during parallel BVI. The change of the rotor advance ratio and oblique descent angle will cause the change of the flow near the rotor, which will change the motion trajectory of the blade tip vortex, and then change the relative angle, distance, and interference phase between the blade and the vortex, thus affecting the blade-vortex interaction noise. vertical force coefficient modifications impact vortex strength rather than trajectory, which directly influence BVI noise intensity.
[1] Sim B W, Lim J W. Blade-Vortex Interaction(bvi) Noise Airload Prediction Using Loose Aerodynamic/Structural Coupling[C] // American Helicopter Society 62nd Annual Forum, Phoenix, Arizo-na,2006.
[2] MARTIN P,BHAGWAT M,LEISHMAN J.Visualization of a helicop-ter rotor wake in hover[R].AIAA 99—3225,1999.
[3] MARTIN P B,PUGLIESE G J,LEISHMAN J G.High resolution trailing vortex measurements in the wake of a hovering rotor[J]. Journal of the American Helicopter Society,2003, 48(1):39-52.
[4] JAIN R,CONLISK A T.Interaction of tip-vortices in the wake of a two-bladed rotor in axial flight[J]. Journal of the American Helicopter society,2000,45(3):157-164.
[5] SWANSON A,LIGHT J S.Shadowgraph flow visualization of isolat-ed tihrotor and rotor/wing wakes[C].Proceedings of the American Helicopter Society 48th Annual Fornm,1992.
[6] LEISHMAN J G,BAGAI A.Challenges in understanding the vortex dynamics of helicopter rotor wakes[J]. AIAA Journal, 1998, 36(7): 1130—1140.
[7] Yu Y H, Tung C, Van Der Wall B, et al. The HART-II Test: Rotor Wakes and Aeroacoustics with Higher-Harmonic Ptich Control(HHC) Inputs-The Joint German/French/Dutch/US Project[C] // American Helicopter Society 58th Annual Forum ,2002.
[8] Mercker E, Pengel K. Flow Visualization of Helicopter Blade Tip Vortices: A quantitative technique to determine the trajectory and the position of the tip vortex pattern of a model rotor[C] // Eighteenth European Rotorcraft Forum, Avignon, France,1992.
[9] Martin P B, Pugliese J G, Leishman J G, et al. Stereo PIV Meas-urements in the Wake of a Hovering Rotor[R].56th Annual Forum of the American Helicopter Society,2000.
[10] Sakoswky P C,Charles B D. Noise Measurement Test Results of AH-1G Operatioal Loads Survey. Bell Helicopter Co.Report 299-099-831,1976.
[11] Splettstoesser W R,Schultzk K J, Boxwell D A, et al. Helicopter model rotor-blade vortex interaction impulsive noise: scalability and parametric variations[J]. Journal of the American Helicopter Society, 1987,32(1):3-12.
[12] ZHAO Y Y,SHI Y J,XU G H. Helicopter blade-vortex interaction airload and noise prediction using coupling CFD/VWM method [J]. Applied Sciences,2017,7(4):381.
[13] 史勇杰,徐国华.飞行参数对旋翼桨-涡干扰噪声特性的影响机理研究[J].航空学报,2013,34(11):2520-2528.
SHI Y J,XU G H. Research on the influence of flight parameters on helicopter rotor Bvi noise characteristics[J].Acta Aeronautica et astro-nautica Sinica, 2013,34(11): 2520-25281(in Chinese).
[14] 史勇杰, 徐国华, 王菲. 直升机旋翼桨–涡干扰脉冲噪声传播特性研究[J]. 南京航空航天大学学报, 2014, 46(2): 212–217.
SHI Y J, XU G H, WANG F. Propagation characteristics of helicop-ter rotor blade-vortex interaction noise[J]. Journal of Nanjing Univer-sity of Aeronautics & Astronautics, 2014, 46(2): 212–217.
[15] 王菲, 徐国华, 胡志远. 大气环境对直升机旋翼桨–涡干扰噪声辐射特性的影响[J]. 南京航空航天大学学报, 2020, 52(2): 304–310.
WANG F, XU G H, HU Z Y. Effects of atmospheric environment on helicopter blade-vortex interaction noise radiation characteristics[J]. Journal of Nanjing University of Aeronautics & Astronautics, 2020, 52(2): 304–310.
[16] 陈文轩.直升机桨-涡干扰试验研究[J].直升机技术,2010, 000(001):1-14.
CHEN W X. The experiment study of helicopter blade vortex interac-tion[J]. helicopter technique,2010, 000(001):1-141(in Chinese).
[17] 刘正江, 黄建萍, 陈焕, 等. 旋翼桨涡干扰噪声特性试验技术研究[J]. 直升机技术, 2019(1): 43–47,42.
LIU Z J, HUANG J P, CHEN H, et al. Study on characteristic of rotor-blade vortex interaction noise[J]. Helicopter Technique, 2019(1): 43–47,42. doi：10.3969/j.issn.1673-1220.2019.01.010.
[18] 刘向楠，刘少腾，周国成，邵天双，陈宝. 旋翼桨–涡干扰噪声特性风洞试验研究[J]. 实验流体力学，2023,37(3): 84-91.
Liu X N, Liu S T, Zhou G C, Shao T S, Chen B, Wind tunnel test research on the characteristics of rotor blade-vortex interaction noise[J]. Journal of Experiments in Fluid Mechanics, 2023,37(3): 84-91.
[19] 杨永东.悬停及前飞状态下旋翼尾迹的显示与测量[C]∥第十八届(2002)全国直升机年会论文.2002.
YANG Y D. Visualization and measurement of rotor wake in hover and forward[C] // The 18th National Helicopter Annual Conference. 2002(in Chinese)..
[20] 袁红刚,李进红,杨永东,王天虹.前飞状态旋翼尾迹测量试验研究[J].实验流体力学,2010,24(4):29-32.
YUAN H G,LI J H,YANG Y D,WANG T H. Test investigation of wake measurement for rotors in forward flight[J]. Journal of Experi-ments in Fluid Mechanics,2010,24(4):29-321(in Chinese).
[21] 江露生,曹亚雄等．共轴刚性旋翼悬停状态桨叶表面压力测量试验与计算研究[J].北京航空航天大学学报.2021,47(12)：2484-2493.
JIANG L S, CAO Y X, et al. Experimental and computional study on blade surface pressure measurement of coaxial rigid rotor in hover-ing state[J]. Journal of Beijing University of Aeronautics and Astro-nautics, 2021, 47(12): 2484 -24931(in Chinese).
[22] 唐朝,招启军,王博.用于BVI噪声试验的新型涡发生器设计与分析[J].南京航空航天大学学报,2018,50(02):17-26.
TANG C, ZHAO Q J, WANG B, PENG N H, ZHU X L. Design and analysis of new type vortex generator for BVI noise experiment, 2018,50(02):17-261(in Chinese).
CJA