空力音の発生機構に関する研究

抄録

The paper describes the generation mechanism of aerodynamic sound produced by the delta wing with attack angles 15 degrees to the uniform flows at a speed of 10 m/s. Flows around the front pillar of an automobile are known as a typical flow field with longitudinal vortex system. The delta wing reproduced well the vortex system. The objective of the present study is therefore to clarify the relationship between vortical structures and aerodynamic sound by using the delta wing. Computational Fluid Dynamics (CFD) analyzed the flow field and aerodynamic sound with unsteady acoustical method. CFD captured clearly unsteady motions of vortices. First large-scale vortices are generated at the tip of the wing and after that along the vortical axis the vortices are broke down to small–scale ones due to the effects of the viscosity and convection of the rotational flows. As a result, it was found that vortices are generated, transported, and diffused in the longitudinal vortex system through energy cascading process.