The Numerical Simulation Of The Flow Noise In The Centrifugal Pump And Noise Optimization

As the development of the computational fluid dynamics and the computertechnology, using the hybrid method to solve the flow noise of the centrifugal pumpbecomes more convenient and faster. Because a lot of achievements have been made in thevibration noise of centrifugal pumps while there are relatively less in the flow noise. Thisdissertation mainly focuses on the flow noise of the centrifugal pump, alow-specific-speed centrifugal pump. This dissertation aims to explore a precise hybridmethod to obtain the flow noise and optimize the flow noise of the centrifugal pumpthrough the geometric design. The main work and the achievements are as follows：1、A three-dimensional model of the centrifugal pump was established and thestructured grid was constructed by ICEM. After verifying the independence of thestructured grid, the entire flow field of the centrifugal pump was calculated with thesuitable boundary conditions, turbulence models and convergence criteria by CFX. Thelarge-eddy simulation was applied to solve the unsteady flow. After achieving theunsteady flow field of the centrifugal pump at different flow rates, the main regions andcharacteristics of the pressure pulsation were analyzed.2、After achieving the unsteady flow field, the result was imported into the softwareACTRAN of the acoustic analogy based on the finite element method. During the acousticcalculation process, the distribution of the instantaneous sound intensity andfrequency-domain sound source of the centrifugal pump was analyzed. The main sourcesof noise in centrifugal pump were different at the different flow rates: turbulence noisedominated at the low flow rate; the discrete noise became apparent at the high flow ratedue to the interaction between the jet-wake of the impeller exit and the tongue.3、The orthogonal optimization method was used to optimize the flow noise of thecentrifugal pump. The main optimization factors were the length of the splitter blade, theoffset angle of the splitter blade and the radius of the tongue. Through the L9(34)orthogonal table nine numerical calculation schemes were established, and the optimalpump type was achieved by the range analysis. The flow noise of the centrifugal pump was calculated by the hybrid method and theoptimization design was carried out, providing the optimization design methods for theflow noise of the rotating machinery in the future.