101 低マッハ数の乱流後流から放射される双極子音と四重極子音の比較(新しい騒音・振動改善技術(1),騒音・振動評価・改善技術)

概要

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The aim of this research is to understand aerodynamic sound generation and propagation from low-Mach number turbulent wake of a bluff body. In order to evaluate both sound pressure strength and propagation pattern, aeroacoustic fields of a square cylinder were numerically calculated with domain decomposition method. The Lighthill tensor was taken from a numerical flow simulation and acoustics filed was calculated by using Finite Element Method. The directivity pattern of the aerodynamic sound showed the dipole distribution at small angle of attack, and therefore the surface pressure term contributes to noise generation. On the other hand, the vortex sound contributions become large at angel of attack of 15 degrees. Conventional method based on the BEM and reduced Curle's equation could not evaluate these results. It indicates that aeroacoustic simulation with Lighthill tensor is useful for the proper visualization of sound directivity and sound wave distribution.
社団法人日本機械学会の論文
2007-07-18