音響摂動方程式を用いた自動車空力騒音の数値シミュレーション

抄録

The most suitable method for aeroacoustics simulation is the direct method based on the compressible Naver-Storkes Equation. However, it is required a large amount of computational resources. The decomposition method of the aerodynamic noise simulation can be solved problems of complex geometry such as automobiles with less computational resources. One of the considerable issues of the decomposition method is which noise sources should be selected in numerical simulations. In order to estimate aerodynamic noise radiated form an automobile, numerical simulations were conducted with an acoustic perturbation equation (APE) and the Lighthill equation (LE). In the aerodynamic noise analysis using the Lighthill tensor, it is possible to obtain the sound field closely related to the flow field including the pseudo sound field, but it is difficult to accurately obtain the sound source term including the second derivative. In the case of the APE, not only it becomes easy to obtain the sound source, but it is also possible to separate the sound and the flow field near the vehicle. This advantage is very important in predicting interior noise. It was also found that the second order differential terms of the pressure field of the flow field contribute little to the sound propagation.