旋翼与紊流场干扰噪声计算

Prediction of Noise Produced by Rotor Interactedwith a Turbulent Flow

本文给出了旋翼与紊流场相互作用产生噪声的理论计算方法。该方法从翼型段在紊流场中作直线运动时的噪声计算分析出发，由理论分析推广到旋翼旋转运动的情况，其中考虑了桨叶上非定常载荷的弦向及展向的非紧致性，叶－叶载荷之间的相关，特别是考虑了由旋翼运动造成的素流场畸变所引起的非各向同性和非均匀性。本文计算了一架模型直升机在＂准悬停＂状态下紊流场的畸变以及相应的干扰噪声谱，并对考虑畸变与非畸变、均匀畸变与非均匀畸变的结果作了比较。结果表明，紊流场的收缩畸变对干扰噪声有显著影响，并对此给出了合理的解释。

This paper gives a brief description of a theoretic prediction method for the noise produced by a rotor interacted with a turbulent flow. The method used here has accounted for the chordwise and spanwise noncompactness effects of the blade surface pressure,the blade-to-blade loading correlations, especially the nonisotropic and non homogeneous turbulence field due to distortion during the rotor in-flow process. The distortion of turbulence field and the resulting noise spectrum are calculated for the case of a model helicopter in the so called 'pseudo-hover'. A comparison is made between the results of isotropic turbulence and non-isotropic turbulence cases, homogeneous and non homogeneous cases, and it is found that the distortion of the turbulence has great influence on the noise spectrum. A rational interpretation of the results is given.