Study On The Effect Of Blade Wrap Angle On Solid-Liquid Two-Phase Flow And Wear Characteristics In Centrifugal Pump

The transportation of solid-liquid two-phase media is involved in many industries such as petrochemicals,deep-sea mining,farmland irrigation,and urban sewage treatment.As the main power equipment,solid-liquid two-phase centrifugal pumps are affected by the movement of solid particles when transporting solid particles,which in turn reduces the hydraulic performance of the centrifugal pump.At the same time,friction and impact occur with the flow components,resulting in wear of the wall surface and a decrease in service life.This article takes a semi-open centrifugal pump as the research object.First,performance experiments and wear experiments under different working conditions were conducted.Then,the CFD-DEM coupling method was used to numerically simulate the semi-open centrifugal pump,and the applicability of the numerical simulation method was verified by combining with experiments.Finally,the effects of particle size,particle concentration,and blade wrap angle on the internal solid-liquid two-phase flow and wear characteristics of the semi-open centrifugal pump were analyzed.The research results can provide data support for the wear-resistant and efficient design of semi-open centrifugal pumps.The core contents of this article are as follows:1.A centrifugal pump solid-liquid two-phase experimental pipeline system was set up to conduct experiments on the performance characteristics of clear water condition and solid-liquid two-phase condition at different flow rates,as well as wear experiments of solid-liquid two-phase condition at rated flow rate.Experimental data for performance characteristics were collected and processed through the control panel of the experimental system.2.A hydraulic model of the semi-open centrifugal pump was created using the 3D modeling software Solid Works,and the two-phase flow inside the pump was numerically simulated based on the CFD-DEM coupling method.By comparing the numerical simulation results with the experimental hydraulic characteristic curve and the distribution of impeller wear positions,the accuracy of the numerical calculation model was verified.3.The effects of different particle sizes and concentrations on the internal flow and wear characteristics of centrifugal pumps were studied.The results show that with the increase of particle size and concentration,the internal pressure of centrifugal pump increases,the degree of streamline disorder in the pump increases,and the turbulent kinetic energy decreases first and then increases.There is a maximum speed area at the impeller outlet.The wear rate of the flow components is closely related to the tangential force on the surface.The wear rate of blade pressure surface increases with the increase of particle size.When the concentration increases from 2%to 8%,the wear rate of the pressure surface gradually increases,and when it continues to increase to 15%,the wear rate decreases.4.The internal flow characteristics of centrifugal pump with different wrap angles were studied.The effects of five blade wrap angles of89~o94~o99~o104~o and109~oon the internal and external characteristics of centrifugal pumps were analyzed.The results show that increasing the blade wrap angle will slightly reduce the head of the centrifugal pump,but the efficiency will increase as a whole.Compared with the head,the blade wrap angle has a more significant effect on efficiency.The influence of blade wrap angle on the internal flow field of centrifugal pump is mainly reflected in the internal pressure and streamline distribution of centrifugal pump.Blade wrap angle can reduce the internal pressure of centrifugal pump and improve the degree of streamline disorder in impeller and volute basin5.The wear characteristics of centrifugal pumps with different wrap angles were studied.The blade wrap angle can affect the position and wear rate of the wear area of the blade pressure surface,and affect the position distribution of the particles.As the wrap angle increases,the wear area of the pressure surface changes from the area near the impeller inlet to the impeller outlet area.Appropriately increasing the wrap angle can improve the followability of the particles to the pressure surface of the blade and reduce the wear of the flow components,but the continuous increase of the wrap angle will reduce the followability of the particles and increase the wear.The decrease of the wrap angle will cause the particles to accumulate at the outlet of the impeller,which will greatly aggravate the wear of the flow components.In general,appropriately increasing the wrap angle can improve the wear of the flow components of the centrifugal pump,but the continuous increase of the blade wrap angle leads to increased wear.