Research On Improvement Cavitation Performance Of A Centrifugal Pump Based On CFD Technique

In the actual operating process of a centrifugal pump,cavitation will reduce the head and efficiency of the centrifugal pump;cavitation corrosion will do great damage to the pump and generate the noises and vibration.So cavitation and cavitation corrosion is one of the main reasons to arise the malfunction of the centrifugal pump.How to improve the cavitation performance of the centrifugal pump is a significant research aspect in the field of fluid mechanism.In the recent years,with the rapid development of the CFD technology and from the centrifugal pump on the mechanism of the internal flow,the numerical simulation is a method to research the cavitating flow inside the centrifugal pump.It is possible that the results by the numerical simulation predicting improve the cavitation performances of the centrifugal pump inner flow.Therefore,numerical method has become a significant tool to performance analyze and optimal design centrifugal pump.Based on the CFD technology,using RNGκ-εtwo equations model and SIMPLEC arithmetic in the commercial software FLUENT,a 3D mixture full cavitating turbulent flow model by Singhal and others is developed for numerical simulation of the steady cavititating turbulent flow in the whole flow passage of a centrifugal pump.In the same design working condition,pressure,speed,distribution of the cavitation volume fraction and the changes of the whole centrifugal pump performances on the prototype design of the centrifugal pump impeller and three impellers of the different import parameters in the internal inner flow are analyzed.It is very significant to improve the cavitation performances of the centrifugal pump, optimal design and to save the energy and cost.The main conclusions are as follows:1.For verifying the veracity of the numerical simulation calculational results,this paper predicted the performances of the prototype centrifugal pump under the non-cavitation flow and the cavitation flow.Compared the numerical simulation datas with the experimental datas, it can conclude that the tendency of the predicted curves basically agrees well with the experimental curves.Prediction values are identical with to experimental values under designing working condition.This provides the foundation for next work.2.Doing simulation for the cavitation flow in the whole flow passage of centrifugal pump,the cavitations mainly occurred inside the impeller,and it is without obvious cavitation happens in the inlet and the spiral case section.The impeller is important influence to the cavitation of the pump.From the NPSH-H curve of the prototype centrifugal pump,it was discovered that the testing value and the numerical simulating forecast value was fitting.The error is in 5%range inner.The curve change trend is basically consistent.The selected cavitation model was accurately forecasting the cavitation function of the centrifugal pump. The numerical simulation can replace the complicated and inconvenient centrifugal pump cavitation experiment.3.By changing the size of the impeller import,it revealed that the impeller import diameters have the best value,which is 155mm and is important significance to increase the centrifugal pump efficiency and to reduce NPSH.4.To increase the import angle of the blade,adopting the larger plus incidence angle, is the result that the cavitation performance of the improved significantly.The import incidence angle is 5°and the import angle of the blade is 24°.5.For the high-speed centrifugal pump,to increase the import flow width of the blade is the result that cavitation performance improved unremarkable.