ジェット騒音 : 第3報, ノズル形状の影響

概要

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The effects of the shape of nozzle-exit, the size of nozzle-exit, the multiple nozzle (jet-interference) etc. on the generation of noise and the mechanism of noise reduction of the widely used noise suppressors are investigated. With the change of the shape or the size of nozzle-exit, the noise intensity per unitfrequency increases proportionally to the second power of the characteristic length of nozzle-exit at the lower frequencies and to the fourth power of that length at the higher frequencies. The interference between jets causes the change of the turbulent velocity-field and reduces the strength of acoustic sources in the mixing region to the degree of the strength in the turbulent region. This accounts for the mechanism of noise reduction of tubular or lobed nozzles. The rate of associated noise-attenuation is evaluated on the basis of experimental results of the turbulent velocity-field. The closer the ratio of the width of nozzle to the space between nozzles to unity on average, the more improved is the characteristics of noise-reduction
一般社団法人日本機械学会の論文
1964-11-25