Study on aerodynamic noise of axial flow fan in ship signal cabinet

Abstract

Abstract In order to study the aerodynamic noise characteristics of axial flow fan in the ship signal cabinet, the aerodynamic noise theory analysis and experimental research were carried out. By comparing and analyzing the vibration and noise spectrum of cabinet, it was determined that the noise of cabinet mainly came from the aerodynamic noise of axial flow fan in the cooling unit of rotating cage. The noise control of cabinet was studied by using the optimal design of the fan installation structure and the application of sound-absorbing cotton. The results show that the noise of fan was discrete noise. The noise increased 2.91 dB(A) when the net was installed in the fan inlet, meanwhile, the energy ratio of high-frequency noise (6000 to 14000 Hz) increased significantly. The sound was sharp. The noise of fan became smaller with the decrease of speed. The peak frequencies of fan noise spectrum were the multiple frequency of fundamental frequency and shaft frequency at different speeds. The sound pressure level was the largest at the fundamental frequency. That is, the noise of fan came from its blades. The noise reduction was 4.24 dB(A) by applying the sound-absorbing cotton on the inner wall of cabinet. The effects of noise reduction were obvious in the 200 to 2000 Hz range. The research results can provide theoretical and experimental support for the optimal design of ship signal cabinet.