Matching Analysis for Transfer and Radiation Law of Sound through Pipe and Sound Source

摘要

At present, there are few researches on the law of pipeline transmission-radiation and the matching between sound source and pipeline in the seawater cooling system, whitch is not strong in supporting the noise control of the seawater cooling system. In view of this, this paper proposes a calculation model of the flow noise radiation in the seawater cooling system by using the plane wave hypothesis and the physical model of single-port pipe orifice radiation. The model adopts the inlet pressure boundary, considers the elastic effect of the pipe wall, and models the internal sound field of the pipe and the local radiation sound field of the pipe orifice through finite element, and combines the infinite baffle and the infinite element to simulate the infinite radiation sound field. The deviation between the critical frequency calculated by the model and the theoretical estimation is 0.73%, and the total transfer loss deviation is less than 3.5%. Based on the calculation and research of the DN175 pipe orifice of a civil ship's seawater cooling system, it is found that there is a mismatch between the total transmission loss characteristics of the pipe and the sound source characteristics of the pump. By adjusting the operation mode, the control effect of the system's leaf frequency line spectrum noise is improved by 30dB.