すきま流れを用いた低騒音減圧機構の可視化による考察

抄録

This research examines the noise characteristics of a slit structure by changing it's height and outer diameter. The slit structure consists of several disks shaped like round sections cut from a cylinder pipe that have been piled up. Compressed fluid enters the center of the piled-disk cylinder and is exhausted through a slit from the inside region to the outside. Because the pressure reduction is performed by a smooth flow through the slit, very quiet pressure reduction can be performed without causing flow turbulence or generating a shock wave. The relation of the Reynolds number and the noise level was clarified, and the visualization equipment was used to check for existence of a shock wave. The results obtained are summarized as follows. (1) When the height of the slit increases, the noise level increases. But, when upstream pressure is 300KPa or greater, regardless of the height and the outer diameter, there is a silencing effect more than 30dB. (2) When the upstream pressure was 600kPa, it was confirmed with visualization equipment that a shock wave did not occur in the slit type structure. (3) When the Reynolds number at exit increases, the noise level increases. Also the characteristics of the noise level is changed near the 2500 Reynolds number. (4) The noise effect increases, when the height of slit decreases and the outer diameter increases.