超音速ジェットのオリフィス板衝突時に発生する流体騒音

抄録

The interference between supersonic jet and structure generates high-amplitude sound field. This study deals with the flow-induced sound due to impingement of the M=1.51 jet on an orifice plate. Two main sound sources are considered. One is Mach waves reflected on the plate surface. The other is the interference sound generated due to the impingement of jet on the aperture. This study tries to determine the governing sound sources with different distance between the nozzle and the plate, and then to suggest the influence of the aperture geometries on the interference sound. At larger distance, the reflection of Mach waves is dominant. At less distance, the sound due to the impingement is relatively increased at higher frequencies. The maximum overall sound pressure level is observed when the distance is approximately ten times of the nozzle diameter. The influence of the aperture geometries appears at higher frequencies, and the frequency characteristics generally correspond to that of the less distance sound. As a result, it is suggested that the interference sound generated due to the impingement of jet on the aperture exists, and it is turned out that the fillet shape of the aperture has the reduction effect of sound pressure.