Study on Acoustic Performance of a Water Muffler for Gear Pump

A water muffler is used for the noise control of a hydraulic pipeline with an external gear pump. An experimental system is established to investigate the acoustic performance of the water muffler, in which the gear pump is utilized as the sound source and power supply. Comparisons between the experimental results of the reference tube, rubber tube, and water mufflers with different inner structures have been made. Numerical simulations on the rubber tube and different water mufflers with various inner structures have been conducted. Simulation results have been compared with the experimental results. These comparison results show that the rubber tube with a compliant wall substantially contributes to the reduction of the noise generated by the gear pump, especially at the high frequency band and relatively low rotate speed of the gear pump. The water muffler results in the enhancement of the noise reduction effect on the rubber tube. With the speed of the gear pump increasing from 1172 r/min to 2344 r/min, the effect of the noise reduction becomes much weaker, since the flow-induced noise gets more intensified. For the rubber tube, in particular, the sound pressure level gets close to that of the reference tube at the speed of 2344 r/min. Moreover, it has been proven by another important experimental result that the length of the inner structure can play a critical role to the flow noise generation.