Numerical And Experimental Investigation Of Cavitation Evolution In High-speed Centrifugal Pump With Inducer

As high speed and high power density are the development trend of the centrifugal pump,development towards high speed requires good working reliability and high cavitation resistance for the centrifugal pump.However,cavitating flow is one of the main reasons to arise the malfunction of high-speed centrifugal pump.An inducer was installed in the upstream of the impeller is the most effective methods to improve the cavitation characteristics of the high-speed centrifugal pump.However,the cavitation easily generate in high-speed inducer passage due to high speed operation.In the lower cavitation number,cavitation instabilities such as the asymmetric cavitation and cavitation surge could be observed in the inducer blade passages,and then seriously affect the operational performance of the high-speed centrifugal pump with inducer.Therefore,an high-speed centrifugal pump with inducer in cavitation condition was investigated by numerical simulation and visual experiments in this paper.The casing of the inducer and impeller was made of the transparent acrylic plastic for visual photography experiments.The cavitating flow in the inducer and impeller blade passage was shot using a high-speed camera.In the present study,the combine of visual experiment and the unsteady calculation were adopted to investigate evolution of cavitation in the high-speed centrifugal pump with inducer.The flow distribution characteristics were analyzed,and effect of cavitation on performance and internal flow field of the high-speed centrifugal pump was found.The results of the study will provide some references for the optimum design of high-speed centrifugal pump,for example the improvement of inducer structure could suppress cavitation generated and reduce the adverse effects of cavitation,thus these will improve the cavitation resistance of the high-speed centrifugal pump.The main topics of this paper are as following:1.The unsteady numerical calculation was performed using the commercial software ANSYS CFX.The numerical results correspond well with the experimental data,validating the reliability of the simulation.2.The internal flow characteristic of centrifugal pump was analyzed by obtaining the contours of the pressure and velocity.The local low pressure location is prone to generate cavitation could be found.Besides,the evolution processes of cavitation and the corresponding pressure coefficient and blade load distribution were obtain by unsteady numerical calculation.The results showed that the inducer blade leading edge and impeller blade root were prone to generate cavitation.With the decrease of cavitation number,the effect of cavitation on blade load distribution is more obvious than the pressure coefficient.3.The method of high-speed photography was adopted in this paper for performing visual experiment,which is that the cavitating flow in the inducer and impeller was shot under the different cavitation number.The analysis of the high-speed image,further reveal the evolution of cavitaion and cavitation instabilities in the high-speed centrifugal pump with inducer.