Study On Cavitation Characteristics And Numerical Simulation Of Semi-open Centrifugal Pump

With the development of the national economy,the centrifugal pump is used more and more widely,but the cavitation of the pump leads to the degradation of performance and the increase of the loss.It not only affects the stability and reliability of centrifugal pump,but also wastes a lot of energy.It is of great significance to study the cavitation of centrifugal pump.In this paper,the performance experiment and cavitation experiment of centrifugal pump were carried out by using the visualized semi-open centrifugal pump test bench.On the basis of experiment,ANSYS software was used to model the experimental pump,and the numerical simulation of the internal flow field and cavitation was carried out,which was confirmed by the experimental results.Finally,the influence of the tip clearance and the interaction between the stator and rotor blades on the cavitation of centrifugal pump was analyzed.The main work is as follows:1.The visual experiment platform of centrifugal pump was built to carry out the performance test and cavitation experiment and draw the performance curve of the centrifugal pump.High-speed photography technology was used to capture the cavitation phenomenon,and the results show that the cavitation occurs at the inlet of the suction surface of impeller of centrifugal pump.According to the geometric parameters of the centrifugal pump,the three-dimensional model was established,and the CFX was used to simulate the internal flow field of the centrifugal pump.The performance curve was compared with the experimental data,and the error was less than 10%.2.The distribution of the pressure field and the volume fraction of the gas in the centrifugal pump under different flow conditions were simulated,and the NPSH-Head curve and NPSH-Q curves are plotted.The results show that the cavitation is generally appeared to the inlet suction surface of the impeller of the centrifugal pump and with the deepening of cavitation,the cavitation zone develops along the flow direction of the rotor blades.This is consistent with the experimental results.With the increase of flow rate,the working condition of cavitation occurs in advance,that is,the value of inlet pressure increases when cavitation occurs.3.The influence of the tip clearance and the interaction of stator and rotor on the cavitation performance of centrifugal pump was analyzed.Firstly,the analysis to the centrifugal pump at different tip clearance and the NPSH-H curves of different tip clearance under the rated flow was drawn and the critical point of the cavitation was found.The results show that in a certain range,with the increase of the tip clearance,the head of centrifugal pump drops and is more prone to cavitation.Then,the influence of the interaction between stator and rotor on the performance of centrifugal pump was analyzed,and the distribution of gas volume fraction and the distribution of blade load were analyzed.The results show that the performance of the centrifugal pump,with the rotation of the impeller,the performance of centrifugal pump,the distribution of pressure field,the distribution of gas volume distribution are periodic changes.The cavitation area occurs at the front of the impeller to 1/5.