Noise generated from Louver exposed to Flow and Countermeasures Effect

Kunihiko Ishihara

This paper describes effects of configuration of the louver and the long hole on aerodynamic noise level. The aerodynamic noise is the most effective noise source of a high speed vehicle on the environmental noise and it is very important for our healthful life to reduce this kind of noise. The aerodynamic noise consists of wind noise generated from the pantagraph and the louvers. Here, the wind noise of louvers and perforated plates are measured and evaluated experimentally by using a low noise wind tunnel. As a result, the following conclusions were obtained. (1) Noise reduction of about 4 dB  is achieved by using the louver of parallelogram frame with 45degree, (2) Noise reduction of about 1dB  is achieved by doubling the number of fin, (3) To make the radius of the frame of the louver large is effective on the noise reduction, although the effect is small, (4) In perforated plate, the hole area to total area is getting small, the noise level becomes small.