旋翼桨尖形状对噪声影响量级的研究

INVESTIGATION OF HELICOPTER ROTOR AEROACOUSTICS FOR DIFFERENT TIP SHAPES

在求解直升机旋翼流场的基础上,预测了旋翼悬停状态下的高速冲击远场噪声,并且针对不同桨尖形状所引起的气动噪声量级作了对比计算,分析了噪声产生机理,并提出了有利于降噪的方法,体现出旋翼CFD技术与Kirchhoff方法相结合的良好应用前景。

This paper describes a new method for predicting high speed impulsive noise generated by a hovering rotor blade. The nonlinear near field solution is computed by an Euler solver, and the pressure signal in the near field can be extracted directly from the Euler solution; moreover,the sound propagation to the far field is computed with linear acoustic methods, namely, the Kirchhoff integration over a surface that completely encloses the rotor blades. Although lacking experimental verification at this time, the results of computed high speed impulsive noise are promising. These calculations show that some benefit can be obtained by taking thin or sweep or taper blade tip shape in reducing the far field noise. Overall, the combined Euler/Kirchhoff scheme provides a powerful new framework for engineering purposes of noise prediction.