NOISE ANALYSIS AND CONTROL SCHEME OF UNDERWATER EXHAUST PROCESS

摘要

Underwater exhaust process always produces strong broadband noise, which not only make the ships and underwater vehicles more detectable, but also have a bad influence on the underwater ecological environment. Therefore, how to suppress the underwater exhaust noise already becomes a subject of widespread concern. However, the underwater exhaust noise contains too many sound sources, which makes it very complex and difficult to control. Aiming at these problems, an experimental system of underwater exhaust noise has been built in this paper. Through a large number of experimental studies, the main sound sources and their corresponding spectrums in the underwater exhaust process have been systematically analyzed. The result shows that underwater exhaust noise in different frequency bands are produced by different sources. The low frequency noise (10Hz～300Hz) which has the dominant position in the underwater exhaust noise is mainly produced by the downstream two-phase flow. The intermediate frequency noise (300Hz～1000Hz) which has a strong correlation with the gas velocity is probably caused by the gas-liquid shear flow. The high frequency noise (1000Hz～5000Hz) is mainly aerodynamic noise generated in the upstream pipeline. Based on these understandings, a four-nozzle scheme is proposed. This scheme reduced the low and intermediate frequency noise as expected.