Numerical Simulation Research On Performance Of Centrifugal Pump Nfluenced By Wear-rings Clearance Change

Recently, computational fluid dynamics(CFD) has been used extensively inpredicting centrifugal pump performance and the internal flows of pumps along withthe development of the computer science and fluid mechanics theory. But at present,people often use simplified model to predict pump performance, ignored the effect ofliquid flow in the clearance of wear-rings and in the pump chamber. And it will bringsome errors of the result. In fact, the leakage of the centrifugal pump is inevitable. Asa non-contact sealing form, wear-rings of impeller can not olny keep the less leakage,but also play a part in the research of the capacity lose and the internal fluid structureof the pump.The paper chooses the single-stage, single-suction, cantilevered and centrifugalpump with balance holes as the main model. Firstly, CFD technology is used forthree-dimensional flow field numerical simulation of whole flow model and thesimplified model. We studied the influence of the model including wear-rings ofimpeller and liquid flow in the pump cavity on the result of the flow field simulationand predicted the performance curve of these two kinds of models. Then the curveswere compared with the experiment curves, and we found that the data of the wholemodel of centrifugal pump numerical simulation is closer to the experiment data. Itwill lay a foundation for further research on the influence of the flow in the clearanceof wear-rings on the performance of the centrifugal pump. Then, based on the CFDnumerical simulation method, the pump function will be analyzed in details throughestablishing different models of different size of clearance of wear-rings, and theeffect of size change of the clearance of wear-rings on the outside characteristics andthe internal flow will be contrasted. By the analysis of numerical simulation data, wedicussed the liquid flow status in the pump chamber after the change of clearance ofwear-rings; the paper contrasted the change of the leakage of different clearance ofwear-rings along with the change of flux and also we analyzed the relations ofpressure difference of into and out the clearance of wear-rings, leakage and flow ratechange after size change of clearance of wear-rings; Analyzed pressure changes offront and back cover board of impeller, and calculated axial and radial force withdifferent clearance of wear-rings. In the study, conclusions are as follow:1) the performance curve of the numerical simulation of the whole model predictionof the centrifugal pump matches well with the experiment curve, but the simplified model is poored matched. This indicated that the whole model is more reliable. At thesame time based on the analysis of the flow in the whole model, we found theprototype pump hydraulic design has some problems.2) the numerical simulation wich extends the clearance of the wear-rings, we foundthe design parameters of the conditions are all changed, and the performance of thepump is obviously poorer than prototype pump.3) the change of clearance of wear-rings affects liquid pressure and velocitydistribution in pump chamber.4) the leakage in the clearance of wear-rings is directly related with the size of theclearance of wear-rings and the leakage will affect the axial force but there is lessimpact to radial force.we need consider the clearance of wear-rings in moleding and numericalcaculation of centrifugal pump and the flow in the clearance of wear-rings is verycomplex. It will affect the performance of the centrifugal pump and the internal flow.The results in this paper can offer a reference for future reasonable design of theclearance of wear-rings and centrifugal pump performance prediction, and it can alsooffer a foundation to the improvement and enhancement of the centrifugal pumpperformance.