Numerical Simulation On The Hydrodynamic Noise Characteristics Of Single Blade Centrifugal Pump And The Optimal Design Of Noise Reduction

As an important part of the vibration and noise of centrifugal pump,the hydrodynamic noise will not only be transmitted to the outside through the solid wall of the pump,but also to the upstream and downstream of the pump through the pipeline,which will stimulate the vibration of other pipeline components in the pump pipeline system.In this paper,a single blade centrifugal pump is taken as the object to study the characteristics of the sound source and the distribution of the hydrodynamic noise in the internal flow field under the deign condition and the off-design condition,and to explore a comprehensive optimization approach that takes into account the hydraulic performance and acoustic performance,which can provide theoretical basis and important reference for the noise reduction optimization design of the single blade centrifugal pump.The main work and achievements are as follows:(1)According to the recommended test procedure of ITTC,the influence of turbulence model and grid scale on the uncertainty of numerical simulation results is analyzed,and the appropriate numerical simulation analysis idea of full flow field is selected.The numerical simulation results show that the disc friction loss on the front and back cover plate of the impeller will affect the efficiency of the single blade centrifugal pump due to the consideration of non-blocking performance.The results show that the performance curves obtained by the numerical simulation of the whole flow field coincides well with the test curve.(2)The frequency spectrum analysis of pressure fluctuation on the surface of blade and volute shows that the energy of pressure fluctuation in the flow field of single blade centrifugal pump is mainly concentrated on the blade frequency and its harmonic frequency in the low frequency range;the smaller the flow rate is,the higher the amplitude of pressure fluctuation on the blade frequency and its harmonic frequency is,and on the pressure surface of blade and volute The components of subharmonic pulsation in the septum increased.The correlation analysis of pressure fluctuation shows that the low-frequency pulsating sound source on the blade surface is mainly concentrated on the blade pressure surface.The blade trailing edge and volute tongue are the sources of high frequency noise.All the monitoring points at the downstream of the volute tongue are fully related to the pressure pulsation components of the leading edge of the tongue at the blade frequency and its harmonic frequency,which shows that the pressure disturbance generated by the dynamic and static interference in the tongue region has a strong propagation ability in the volute channel.The high frequency pressure pulsation sensors are used to collect the pressure pulsation data of the volute wall,which are compared with the numerical simulation results.The analysis shows that the simulation curves of the pressure pulsation are close to the test curves,and the consistency are good,which indirectly shows that the dipole sound sources obtained from the numerical simulation of the transient flow field can be used for the analysis and calculation of the hydrodynamic noise.(3)The energy of the internal noise in the single blade centrifugal pump is mainly concentrated in the blade frequency and its harmonic frequency in the low frequency range.With the increase of the flow rate,the blade frequency harmonic noise in the low frequency range presents a significant decline.The frequency spectrum analysis of the sound power level under different flow rates shows that the distribution characteristics of the pressure fluctuation have a direct impact on the internal hydrodynamic noise of the single blade centrifugal pump,and the influence of the volute dipoles and the impeller dipoles should be considered comprehensively in the internal sound field simulation calculation.Compared with the internal noise,the external noise energy of the single blade centrifugal pump is lower.Although there also have noise peaks at the blade frequency and harmonic frequency,they are significantly lower than the noise peaks at the first three order constrained mode frequency(< 2500Hz).It shows that the external radiation sound of the pump body is affected by the pressure fluctuation of the internal flow field and the natural frequency of the pump body.(4)Starting from the blade parameters,the optimal Latin hypercube sampling is used for the test design,and the polynomial response surface method is used as the approximate method to construct the proxy model.Finally,the NSGA-Ⅱ multi-objective genetic algorithm is used to carry out the global optimization,and the Pareto solution set is obtained,from which the optimal combination of blade parameters,which takes hydraulic performance and low noise into account,is selected.The numerical simulation results show that the impeller designed based on this parameter combination can reduce the total sound power level of the internal noise by about 2dB without reducing the hydraulic performance of the single blade pump.