改进型CLOR桨尖旋翼悬停状态气动噪声特性试验与预估分析

Investigations on acoustic characteristics of rotor with improved CLOR bladetip in hover based on experimental and prediction method

  • 摘要: 结合试验及数值模拟方法对具有改进型CLOR(CLORII)桨尖模型旋翼悬停状态气动噪声特性进行研究。在CLOR桨尖旋翼基础上,兼顾旋翼噪声特性和气动性能,对旋翼气动外形进行改进。为在获得高气动性能(大拉力)的同时限制旋翼气动噪声的过快增长,采用曲线前后掠组合、尖削及多种翼型分段配置等设计方法,以抑制跨声速流范围,达到降低气动噪声的目的。作为参考验证,文中还同时进行了相同实度的矩形桨叶、常规后掠新型桨尖的旋翼气动噪声特性的测量试验。考虑到传播距离和方向角(与桨盘平面的夹角)等因素对噪声辐射特性的影响,试验中对不同观测点的噪声进行了测量。同时为反映桨尖马赫数(压缩性)对旋翼噪声特性的影响,还测量了多种转速下的旋翼噪声特性。为充分分析新型桨尖旋翼的噪声特性,本文采用了基于CFD/Kirchhoff方法的旋翼噪声分析方法对试验中较难开展的高桨尖马赫数状态进行预估分析,分别给出了上述不同桨尖旋翼表面等马赫线、近场声压时间历程等跨声速流场细节。通过试验与数值分析,得出了关于CLORII型桨尖旋翼气动噪声特性的影响规律,与参考旋翼相比验证了该新型桨尖旋翼在提高气动性能的同时具有良好的噪声特性。

     

    Abstract: The aeroacoustic characteristics of model rotor with improved CLOR (CLORII) bladetip in hover are investigated through tests and numerical simulations. Firstly, the shape of rotor blade is improved based on CLOR bladetip considering both aeroacoustic characteristics and aerodynamic performance. In order to obtain preferable aerodynamic performance (high rotor thrust) and suppress the rapid increase of rotor noise, curvilinear forwardbackward swept, taper and airfoil configuration are adopted so that the transonic region is restrained and the noise level of rotor is decreased. Then, the aeroacoustic characteristics of rectangular planform blade and constant swepttip blade with the same solidity are measured in present work for validation. In consideration of the effects of radiation distance and orientation angle (inclined to rotor disk plane) on acoustic characteristics of rotor, acoustic measurements are conducted at different observation locations in tests. Furthermore, acoustic measurements are carried out at various rotor rotation speeds to evaluate the influence of blade tip Mach number (compressibility) on acoustic characteristics of rotor. Finally, a rotor acoustic analysis approach based on CFD/Kirchhoff method is established, and the acoustic characteristics of CLORII bladetip have been comprehensively investigated under high blade tip Mach number conditions which are difficult to be conducted in tests. Details of the transonic flowfield of abovementioned bladetips, such as Mach contour and nearfield pressure contour, are provided respectively. Through tests and numerical analysis, the effects of CLORII bladetip on aeroacoustic characteristics are obtained, and rotor with the present advanced tip can simultaneously enhance aerodynamic performance and retain better acoustic characteristics comparing to reference rotors.

     

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