Study On Wear Characteristics Of Centrifugal Pump Under The Condition Of Sandy Water

The research is supported by the National Natural Science Foundation of China"study on cavitation characteristics and erosion mechanism of hydraulic machinery under the condition of sandy water"（project number:51979126）.The centrifugal pump is widely used in the Yellow River basin.when conveying a variety of mixed sediment flow,the existence of sediment particles will have friction collision with the flow wall,resulting in its wear and damage.seriously affect the stability and service life of the centrifugal pump.Aiming at the wear problem of centrifugal pump,a semi-open centrifugal pump is selected as the research object in this paper.the effects of flow rate,sediment concentration and physical properties of sediment particles on the wear of flow parts of centrifugal pump are studied by means of experiment and numerical simulation.The main contents are as follows:1.The solid-liquid two-phase flow test rig of the centrifugal pump was set up,and the energy performance,pressure fluctuation,vibration and wear tests of the centrifugal pump were carried out,and the energy characteristics,flow characteristics and wear changes of two kinds of mixed sediment particles transported by the centrifugal pump were studied.The results show that:（1）The higher the sand concentration of the centrifugal pump is,the smaller the head and efficiency are,but when the sand concentration is less than 1%,the efficiency of the centrifugal pump decreases lesser and remains basically unchanged;（2）The amplitude of pressure fluctuation decreases with the increase of flow rate and increases with the increase of sand concentration;（3）The amplitude of vibration velocity at each measuring point decreases with the increase of flow rate and increases with the increase of sand concentration.（4）The impeller wear of the centrifugal pump first occurs at the blade entrance,and with the increase of wear time,the blade working face,rear cover plate and back face are worn one after another,among which the outlet wear of the blade working face is the most serious.（5）The greater the flow rate of the centrifugal pump,the more serious the impeller wear;the higher the sand concentration is,the deeper the impeller wear is.2.The distribution of sediment particles with various particle sizes is fitted by Rosin-Rammler distribution function,the Euler-Lagrangian method is selected to calculate the two-phase flow in the centrifugal pump,and the Grant-Tabakoff wall rebound model is selected to describe the collision process between particles and the wall.Compared with the advantages and disadvantages of various wear models,Mclaury wear model is selected as the wear calculation model.The water domain modeling and meshing of the centrifugal pump are carried out,and the external characteristic results of the numerical simulation and the wear calculation results are compared with the test values,respectively.The maximum error of the pump head is3.4%,and the maximum error of the efficiency is 1.9%.The calculation results of the wear position are basically consistent with the test,and the accuracy of the calculation method is verified.3.Based on the characteristics of sediment-laden flow in the Yellow River basin,the effects of different sediment particle size,sediment particle density and sediment particle shape on the wear characteristics of centrifugal pump components are studied.The results show that:（1）With the increase of the average sand particle size,the wear of the blade working face decreases gradually,and the wear of the blade back,rear cover and volute increases gradually;the larger the average sand particle size is,the more serious the local wear of the flow parts of the centrifugal pump is,and when the average sand particle size increases from 16μm to 45μm,the change of the maximum wear rate of the blade working face is the biggest,and the maximum wear rate increases 3.72×10^-4kg/（m²s）.With the increase of the average sand particle size,the total wear rate of the blade working face decreased,and the decrease speed was larger,and the total wear rate of the blade back,rear cover and volute increased gradually,especially on the back of the blade.When the average sand particle size increased from 16μm to 45μm,the change of the total wear rate of the blade working face was the biggest,and the total wear rate decreased 0.0244kg/s.（2）With the increase of sand density,the overall wear degree of the flow parts of the centrifugal pump deepens;the greater the sand density,the more serious the local wear of the flow parts of the centrifugal pump,when the sand density increases from2100kg/m³to 2900kg/m³,the maximum wear rate and the total wear rate of the blade face change greatly,the maximum wear rate increases 2.88×10^-4kg/（m²s）,and the total wear rate increases 0.0172kg/s.（3）When the sand is irregular sand with edges and corners,the greater the shape factor of the sand is,the greater the wear of the blade working face and volute is,and the smaller the wear of the back of the blade and the back cover is;when the sand is not angular,the wear of irregular sand on the flow parts of centrifugal pump is more serious than that of spherical sand.The maximum wear rate of irregular sand with edges and corners on the flow wall surface of centrifugal pump is higher,which is much higher than that of spherical sand,and when irregular sand is transported by centrifugal pump,the local wear is the most serious on the back of blade.When the sand particles are angular with shape factors of 0.67 and 0.81,the total wear rate of the back cover plate and volute of the centrifugal pump is larger,and when the sand particles are sub-ball and ball with shape factors of 0.98 and 1,the total wear rate of the working face of the centrifugal pump is larger,and the shape of sand particles has a great influence on the total wear of the flow parts of the centrifugal pump.