プレートから放射される空力音に関する研究 : 第1報 : 風洞実験および数値解析の基づく音場の考察 : 流体工学, 流体機械

概要

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The intensity and the directivity of the aerodynamic sound generated from a plate having semicircular edges are investigated by wind tunnel experiments and numerical analysis. From the experiments, it is indicated that the intensity of the aerodynamic sound isn't proportional to U^6 and the dipole-type directivity of the aerodynamic sound is biased toward the upper stream side with the increase of c/λ, where U, c, and λ are the wind velocity, the plate chord-length, and the acoustic wave-length, respectively. Numerical analyses for various thickness plates are performed in order to be compared with the experimental data. A combined method which consists of a two-dimensional computational fluid dynamics (CFD) code and a two-dimensional aeroacoustic code based on the Lighthill's equation is used. As a result, the calculated sound fields are qualitatively in reasonable agreement with the experimental ones. Moreover, the identification of the source locations are performed by the numerical method. It is found that the Lighthill's sound source term becomes large near the reattachment of a separation bubble and the trailing-edge. The latter source is the main contributor in the radiated sound field because the former is cancelled by the mechanism based on phase variations.
社団法人日本機械学会の論文
2001-01-25