円形空気薄膜層を壁内面に有する機械開口部からの音響放射 : 離散周波数音の減音効果について

概要

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Purpose of this study is attenuation of sound radiated from ventilation apertures and holes setting up on all apparatus by using circular slit resonator. The circular slit resonator composed of thin air layer that is radial expansion with very short axial length was set up machinery wall. The circular thin air layer acts as an acoustic resiatance, inertance and capacitance. The noise was reduced greatly at a natural frequency of the circular thin air layer that shows symmetrical circular mode of standing wave. In this paper insertion loss, IL, of the circular slit resonator designing to reduce discreat frequency noise(DFN)radiated from axial flow fan was clarified on both experimental and theoretical studies. The insertion loss, IL, of the circular slit resonator was measured by using sound intensity method. IL indicates narrow peak at resonant frequency and it strongly depends on the slit depth and slit width. IL level increases with the slit width, thickness of resonator panel and separator. The prediction of IL by the calculation model is approximately accurate.
社団法人日本機械学会の論文
2000-06-25