基于Mohring声类比的开式转子发动机噪声分析

Open-rotor engine noise analysis based on Mohring acoustic analogy

为了系统地研究非均匀流场中开式转子的噪声特性,运用计算流体动力学(CFD)和计算气动声学(CAA)无限元法相结合的方法,对开式转子的频域噪声做了数值预测。通过采用基于可压缩修正的Spalart-Allmaras湍流模型对非均匀流场中开式转子气动特性进行分析,运用声学无限元方法,引入平均流场并将其插值到声学网格作为背景流场,对转子噪声和噪声传播进行数值模拟,并对特征点做频域分析。由噪声分布云图和远场特征点频谱曲线分析得出:非均匀流场中开式转子发动机的峰值辐射噪声主要集中于低频范围,噪声最大值为142dB,峰值噪声频率为115Hz,随着频率增加,交替出现多个局部峰值声压,噪声衰减速度减小。为下一代开式转子发动机噪声预测提供一种方法。

In order to systematically study the characteristic of open-rotor noise in nonuniform flow field,CFD（computational fluid dynamics）/CAA（computing aerodynamic acoustic-s）hybrid method of the open-rotor aerodynamic noise was set up.The aerodynamic characteristics of open-rotor were analyzed through compressible modified Spalart-Allmaras turbulence model method,then,the open-rotor noise and noise transmission were numerically simulated by acoustic infinite element method.At the same time,the average flow field and its smooth interpolation were introduced to acoustic grid as a background flow field.Taking into account the noise distribution chart and the far field feature point spectrum curve,it was concluded that non-uniform flow field radiated noise in the open-rotor engine was mainly focused on low frequency range,the maximum noise was 142 dB,and the maxi-mum noise frequency was 115 Hz.With the increase of frequency,multiple local peak sound pressures appeared alternately,and noise attenuation rate decreased.A method was proposed to predict the noise for the next generation open-rotor engine.