318 4 点マイク法による定常流下の多孔板の減衰特性同定研究

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Acoustic damping mechanism of perforated panels was studied by using four-microphone measuring technique. Damping mechanism of perforated panels are composed of viscousity in boundary layer around a small hole and dynamic pressure loss at that hole. Without steady flow condition, Melling[5] summarized theoretical damping models for perforated panels. Hayama and et al[3] derived theoretical model for dynamic pressure loss under steady flow condition. In this paper, acoustic damping of perforated panel was identified experimentally from sound pressures and particle velocities at both frontal and rear surfaces of the perforated panel. Sound pressure and particle velocity on the frontal surface are calculated from sound pressures measured at two position in front of perforated panel. Sound pressure and particle velocity on the rear surface are also calculated. The 0.8mm-thick perforated panel with 2mm diametrical holes was tested at various sound pressure levels and various steady flow speeds. Identified damping characteristics are independent of amplitude at low sound pressure level without steady flow. Identified one at high sound pressure level without flow is proportional to root-mean-square value of particle velocity. Identified one with steady flow is proportional to flow speed when particle velocity is less than flow speed. Identified damping characteristics for perforated panel at various condition are compared with Melling's model and Hayama's model and reasonably good agreements are achieved.
社団法人日本機械学会の論文
2002-09-13

318 4 点マイク法による定常流下の多孔板の減衰特性同定研究

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