Aerodynamic Noise Generated from Punched Small Holes at Changing arrangement of Holes and Direction of Air Flow

Abstract

This study deals with the aerodynamic noise generated from perforated metal plate. Perforated metal is produced by punching the sheet metal using a press die. It has two kind of direction by characteristic cross-sectional shape. This experiment is defined as one direction is “Expansion” and the other direction is “Shrinkage”, and evaluation of flow velocity is “Average flow velocity from per hole”. In the experiment, the aerodynamic noise generated from the perforated metal is measured. The number of holes, direction of the plate and “average flow velocity from per hole” are varied in experiment. According to experimental results, When the direction of the perforated metal is “Expansion” and “Average flow velocity from per hole” is over 35m/s, partial overall value is 20~30dB larger than “Shrinkage”. In the case of “Shrinkage”, cross-sectional shape and arrangement of holes affect on flow field and aerodynamic noise.