パンチングメタル板通気時の卓越周波数騒音の発生に関する開孔条件の検討

抄録

This study deals with aerodynamic noise generated from perforated metal plate. Perforated metal plate has two flow direction and the aerodynamic noise are varied by flow direction. At the expansion direction, large prominent peak in the frequency characteristics is observed. That prominent peaks are also observed in the experience by one hole and seven holes. In the experiment, velocity fluctuation of jet flow issuing from the hole is measured by a hotwire anemometer. Distribution of sound source is expected by numerical value of coherent output power (COP) calculated by velocity fluctuation and coherence function. Coherence function is defined between generated noise and velocity of jet flow. As the result, under seven holes, the COP value in the shrinkage direction is larger than that in the expansion direction. At the time of prominent frequency noise, the noise generated by the vibration of the perforated metal plate is dominant and it is considered that the aerodynamic noise is reduced.