Abstract: There are three types of noise in rotary compressors: mechanical noise, aerodynamic noise, and electromagnetic noise. Among them, aerodynamic noise contributes significantly to compressor noise, and it mainly occurs during the exhaust process of the compressor. Currently, setting up a resistant muffler at the compressor exhaust port is a common method to reduce aerodynamic noise in engineering. Therefore, designing a muffler with good noise reduction effect is of great practical significance. The industry generally uses transmission loss to measure the noise reduction effect of adversarial silencers, but the method can’t consider the pulsating noise of the fluid inside the silencers. Firstly, the noise reduction effect of two different types of silencers is evaluated using the commonly used transfer loss curve in the industry. Then, the CFD commercial software is used to simulate the pressure pulsation inside the muffler for pulsation noise evaluation. Finally, the muffler effect of two kinds of structure muffler is verified on a certain type of compressor. The simulation and experimental results indicate that the fluid dynamic noise inside the muffler cannot be ignored, the transfer loss curve cannot measure the pulsating noise and it is feasible to use CFD software to simulate pressure pulsation and evaluate pulsating noise. The research results provide certain reference value for the design optimization of built-in silencers in rotary compressors.

Key words: Muffler, Transmission loss, Pulsating noise