Hydraulic Optimization Of Multi-Stage Centrifugal Pumps And Numerical Study On Cavitation Performance

Multi-stage centrifugal pump is one sort of the most widely used industrial pumps atpresent, it is of great significance to optimize its performance. Cavitation performance ofmulti-stage centrifugal pump is always an important index that effects the stable operationof pumps. Cavitation will cause many problems such as the decrease of energycharacteristics, the vibration and noise of machines, the damage of flow components and soon. How to effectively optimize and predict cavitation performance is an important part ofmulti-stage centrifugal pump cavitation reseach. With the great development of CFDtechnology applied in numerical simultion of hydraulic machinery interal flow, the CFDsoftware has become an important tool for optimal design. Combined with turbulencemodel and cavitation model, the numerical simulation of cavitation flow in pumps becomepossible.This paper used standard k-ε turbulence model and Rayleigh-Plesset cavitation modelin ANSYS CFX softwre to predict the cavitation performance of multi-stage pump. On thebasis of a lot of theory and experience, the paper put forward an optimal scheme. Theoptimization of suction chamber included the improvement of the overall structure. Thepaper put forward the structure of symmetric semi spiral. Through theoretical study andnumerical simulation of the internal flow in new model, the paper discussed the effect ofthe suction chamber on the first stage impeller. The improvement of impeller is changing itsstructure parameters, including inlet setting angle, the blade shaft surface contour, the shapeof blade head etc.. The effect of various parameters on cavitation is analyzed through theory,the changes of impeller cavitation flow is improved through the numerical simulation. Thenthe paper obtained the energy characteristics curve and cavitation characteristics curve.The research shows that, the suction chamber with symmetric semi spiral structure notonly reduces the water loss, but also makes the entrance flow field of the impellersignificantly improved; The impact loss of new first stage impeller head reducessignificantly, cavitation inception has been delayed, bubble distribution on the bladebecomes smaller. Moreover the new model has better performace than the original model invarious situations. After optimization, both the efficiency of overall model and the criticalNPSH have been significantly improved.