The Research on Source of Aerodynamic Noise from Ventilating Perforated Metal Plate

Abstract

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. 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. The result discovers prominent peak has different distribution of sound source and prominent peak that has sound source far from perforated metal plate disappears by interference of jet flow.