Numerical Research On The Inner Flow-Induced Noise For Rotor-type Oil Pump

As the noise regulations are getting more and more rigorous, oil-pump noise has been concerned gradually by researchers which is the major noise source of engine noise. Due to the smooth contact of inner and outer rotor, the mechanical noise of rotor type oil-pump is lower than the gear oil-pump’s. Therefore, it is important to study the fluid noise of rotor type oil-pump.According to Natural science foundation of Hunan province (12JJ9015)-"Study the noise control mechanism of rotor type oil-pump base on sound-vibration coupling".CFD software and acoustic solver software are used to simulate the flow-induced noise of rotor type oil-pump based on acoustic finite element and infinite element method. The main innovation and research are as follows:(1)Based on the aeroacoustics Lighthill equation and FW-H equation considered the fluid flow solid boundary conditions, the paper researches three sound source caused by fluid flow and thinks of that monopole and dipole sound source is the main source within the rotor type oil-pump.(2)The flow model of sound field was built by combining with the characteristics of CFD software and acoustic software, and the numerical simulation of flow field in the rotor type oil-pump was carried out under unsteady state which got the flow characteristics under different speeds, static pressure distribution, vorticity distribution and pressure pulsation statistical analysis. Lighthill acoustic analogy method was utilized to extract the sound source, and the time-domain signal was converted into frequency-domain signal by fourier-transform. Source distribution and sound pressure level of the monitoring points was got by simulating the radiation sound fiels of the pump.(3) This paper puts forward some methods to reduce noise, such as increasing the number of teeth on the inner and outer rotor, opening the unloading tank, reducing the resistance and improving the precision of rotor. Increase the number of teeth on the inner and outer rotor is verified by test which can reduce the flow noise.