Control of Blade-Passing Radiation Noise Throughout the Baffled Open End for a Seawater Cooling System Using Muffler-Pipeline Acoustically Coupling Effect

In engineering design, the acoustic coupling between the muffler and the pipeline is usually not considered. The noise control effect of the muffler is evaluated by the direct superposition of the noise transmission loss of the muffler pipeline flow and the pipeline transmission loss, which leads to the problem of poor actual noise control effect of the muffler. Through theoretical analysis, it is found that the installation position of the muffler is the key factor affecting the acoustic coupling effect between the muffler and the pipeline. Aiming at the problem of 300 Hz blade-passing frequency spectrum noise control of civil 220 t/h centrifugal pump, the acoustic calculation model of the pipeline system is established by acoustic finite element method, and the acoustic coupling effect between the muffler and the pipeline is analyzed. The results show that when acoustic coupling effect is considered, the frequency of the total transmission loss curve of pipeline system changes significantly through the characteristics, and the overall transmission loss increases by 15.9 dB. When the seawater muffler is installed at a position 1/4 wavelength away from the pump group interface, the overall level of radiated noise is reduced by 10.4 dB and the noise of blade-passing frequency line spectrum is reduced by 20.8 dB compared with the position 5/8 wavelength. It can be seen that reasonable use of acoustic coupling effect between muffler and pipeline can significantly improve the control effect of pump group blade-passing frequency line spectrum noise.