Study On Flow And Flow-Induced Noise Characteristics Of Multi-stage Centrifugal Pump

With the development of pump application technologies,higher and higher requirements are put forward for pump operation stability including vibration and noise,especially in important fields such as national defense,military and precision instruments.Hydrodynamic noise is an important component of pump noise,which involves many disciplines such as hydrodynamics,acoustics,vibration and so on.The study of internal flow noise mechanism of centrifugal pump is essential for improving the operational stability of pump.In this paper,the unsteady numerical simulation of multi-stage centrifugal pump is carried out using SST k-? turbulence model.The dipole source file is derived and the acoustic simulation is carried out by direct acoustic boundary element method.The acoustic field characteristics of multi-stage centrifugal pump and its coupling relationship with the flow field are analyzed.The main conclusions are as follows:(1)The analysis of transient results in multi-stage centrifugal pump shows that the turbulent kinetic energy and other physical quantities change most dramatically in the interface area between the rotating and stationary components due to the mutual motion between the rotating and stationary components.The pressure in the impeller domain exhibits a gradient change,and after the fluid enters the stationary part,the pressure distribution is not uniform.The most intense pressure fluctuation is at the interface area between the stationary part and the rotating part.Because of the structure of the stationary part and the rotating part,the frequency peak value of the pressure fluctuation of the two parts is different,and the peak value of the pressure fluctuation of the stationary part appears.At impeller blade frequency and frequency doubling,the peak pressure fluctuation of rotating parts occurs at guide blade frequency and frequency doubling.(2)Acoustic simulation of flow-induced noise in different operating conditions of multi-stage centrifugal pumps shows that flow-induced noise is mainly composed of discrete noise and broadband noise.The sound pressure level under non-design conditions is greater than the sound pressure level under design conditions.It is known from the sound pressure level frequency response that the characteristic value of the stationary dipole sound source field point is mainly the impeller's frequency and its multiplication frequency,and the characteristic value of the rotating dipole sound source field point is the axial frequency and its multiple frequency.The sound pressure level frequency response of the static dipole sound source field point and the pressure pulsation are particularly obvious at the impeller's frequency and the frequency doubling,that is,the pressure pulsation has a significant influence on the discrete noise in the noise caused by the flow,and the sound pressure level frequency response and pressure pulsation coupling phenomenon of the rotating dipole source field are not obvious.