428 渦の干渉による空力騒音の発生メカニズムについて(S35-2 乱流渦構造(2),S35 乱流渦構造)  [in Japanese] 428 Mechanism of Aerodynamic Noise Generated by Vortices Interaction  [in Japanese]

The mechanism of aerodynamic noise generated by vortices interaction was investigated applying experiment and numerical simulation. The study focuses on the aerodynamic noise generated near side window of production automobile. In simulation, the flow filed was firstly analyzed by Finite Differential Method (FDM) with 3^<rd>-order upwind scheme, then Powell's acoustic analogy was applied to evaluate the acoustic source. Furthermore, the velocity fluctuation and acoustic source were clarified by the use of experiment. It is found that the interaction between vortices separated from front-pillar and door-mirror results in the instability of boundary layer, which induces the aerodynamic noise near side window. By optimizing the relative location between front-pillar and door-mirror, the boundary layer instability can be inhibited, and then the noise is reduced.