Consideration on aerodynamic self-excited resonant tone of semi-cylindrical cavity

Abstract

Regarding aerodynamic self-excited tone accompanied by acoustic resonance generated from a semi-cylindrical cavity, we estimated characteristics of the secondary flow inside the cavity based on the results of acoustic mode numerical analysis, the already measured distribution of flow velocity turbulence and the flow pattern as results of flow-visualization. Resonant mode which is similar as the flow pattern could be found through acoustic analysis although the resonant frequency is higher than measured tone frequency. This mode consists of one antinode in radial direction and four antinodes in circumferential direction. And we have considered the mechanism of vortex shedding on open edge of the cavity during resonance. It was inferred that the secondary flow, which becomes stronger in the antinode region of the sound pressure distribution due to resonance, influences the periodicity of vortex shedding. It would be the remaining subject to make clear the difference of the resonant frequency between experimentally measured and numerical analyzed.