平板上の物体によるはく離流れから発生する騒音 : 発生音の理論的検討と実験による検証

概要

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Theories of aerodynamic noise generation from solid boundaries in airflow at low mach nmbers have been proposed by Curle and Powell-Howe. Acoording to the Curle's theory the noise sources are pressure fluctuations on the solid boundaries. On the other hand Powell-Howe showed that vortices in space are also the significant noise sources. The present authors verify that vortices in space can be effectively transformed to the pressure fluctuations on a solid boundary when the vortices approach in close vicinity of the solid boundaries. In the present experiment the parameters related to the noise generation such as the sound pressure level generated from separated airflow caused by a forward facing step or a fence on a flat plate, the pressure fluctuations on the solid boundaries and the flow velocity fluctuations were measured. By the examination of correspondence between the experimental results and the theories, it has proved that the agreement between the two is better in the Powell-Howe's theory than the Curle's theory. This result indicates that in the present experimental condition the dipoles of vortices distributed in space are stronger than the dipoles distributed over the surface of solid boundaries.
社団法人日本機械学会の論文
1998-03-25