Research On Hydraulic Performance And Internal Flow Field Of Centrifugal Pump Based On Orthogonal Test

In order to study the working efficiency and internal flow field of a centrifugal pump,this article takes a single stage centrifugal pump as the research object.Solid Works modeling is used,ICEM CFD is used to draw grids,DEM-CFD coupling calculation method is used,and numerical simulation results are verified through experiments.The parameters affecting the working efficiency of a centrifugal pump and the internal flow field are studied through orthogonal experiments.Many scholars have studied the flow of solid-liquid two-phase flow inside centrifugal pumps,but the parameters that affect the efficiency of centrifugal pumps are still not clear enough,and the analysis of particle motion trajectories and vortex characteristics inside centrifugal pumps is also not clear enough.This article uses four factors and three levels of orthogonal experiments to study the effects of rotational speed(2650r/min,2850r/min,3050r/min),inlet speed(1m/s,1.5m/s,2m/s),viscosity coefficient(0001pa ? s,0.01 pa ? s,0.1pa? s),and sphericity(0.84,0.91,1)on the hydraulic performance of centrifugal pumps.The intuitive analysis method,range analysis method,and variance analysis method are used to analyze the primary and secondary effects of different factors on the hydraulic performance of centrifugal pumps,The optimal parameter combination with the highest hydraulic performance of the centrifugal pump was obtained through orthogonal experiments,and then the single factor analysis method was used to analyze the internal vortex characteristics and flow field of the centrifugal pump.The research results are as follows:(1)The intuitive analysis of head,efficiency,and particle throughput through orthogonal experiments shows that the hydraulic performance of centrifugal pumps varies greatly under the influence of different factors and levels.Through range analysis,it was found that the main factors affecting the head are C(fluid viscosity),D(impeller speed),A(inlet speed),and B(particle sphericity).The optimal operating conditions are: inlet speed is 1m/s,sphericity is 1,fluid viscosity is 0.01,and impeller speed is 3050r/min;The factors that affect efficiency from primary to secondary are: C(fluid viscosity),D(impeller speed),B(particle sphericity),A(inlet speed).The optimal operating conditions are: inlet speed is 1.5m/s,sphericity is 1,fluid viscosity is 0.01,and impeller speed is 3050r/min;The influencing factors on particle passing rate from primary to secondary are A(inlet speed),D(impeller speed),B(particle sphericity),and C(fluid viscosity).The optimal operating conditions are: inlet speed is 2m/s,sphericity is0.84,fluid viscosity is 0.01,and impeller speed is 2850r/min.The results of variance analysis are consistent with those of range analysis.(2)The regularization helicity analysis found that when the rotation of the blade periodically occurs or disappears,two pairs of relative vortices will appear,one pair of vortices is located at the top of the blade,and the other pair of vortices is located at the bottom of the blade.The regularization helicity of the volute part is a clockwise vortex or a counterclockwise vortex.The regularization helicity at the pipeline,clockwise and counterclockwise vortices are distributed unevenly,showing a random distribution state.(3)Using the Q-criterion calculation method,the vortex core isosurface inside the centrifugal pump under 9 sets of tests were calculated and colored with velocity V.Under different operating conditions,the vortex distribution at the impeller blades of a centrifugal pump presents three different situations.Firstly,the vortex distribution at the blades is relatively small.Secondly,the vortex distribution at the blades is relatively discrete and randomly distributed.The equivalent surface vortex presents an irregular state.Thirdly,the vortex distribution at the blades has a regular shape and is symmetrically distributed.The vortices produced by the volute also have three states: firstly,the surface is smooth and the distribution inside the volute flow channel is relatively uniform;The second is that the front part of the pipeline vortex is intact,and separation occurs in the latter part of the pipeline vortex;The third reason is that the vortex surface of the volute is rough and there is a hollow in the middle.The vortices in the outlet pipeline have two different states: one is that the surface of the vortices in the pipeline is smooth,forming a pipeline vortex;The second is that the vortex in the pipeline exhibits a spiral distribution and a certain degree of distortion.(4)As the fluid velocity increases,the maximum velocity area of the fluid decreases,and the fluid trajectory inside the centrifugal pump gradually stabilizes.Vorticity analysis found that as the flow rate increases,the vorticity changes inside the centrifugal pump gradually stabilize,with the large vorticity area gradually approaching the blade and the small vorticity area approaching the volute.Analysis of particle motion trajectories found that there are four typical particle motion trajectories inside the centrifugal pump: the first type of particle motion trajectory is the rotation of particles at the inlet of the impeller;The second type of motion trajectory involves particles entering the area behind the volute and then flowing out of the centrifugal pump with the flow of fluid.The third type of motion trajectory particles enter the volute area near the tongue driven by the impeller,and flow inside the volute driven by the swirling flow.The fourth type of particle motion trajectory is a vortex driven by the rotation of the centrifugal pump impeller after the particles enter the interior of the volute area,and flow out of the centrifugal pump along the volute curve.(5)As the impeller speed increases,the velocity of the fluid inside the impeller shows an increasing trend;The average retention time of particles inside the centrifugal pump is decreasing;The maximum retention time range inside the impeller increases,and the movement inside the centrifugal pump is relatively chaotic,with no change in the minimum retention time of particles.(6)Research has found that there are three areas with high turbulent kinetic energy,including the blade head,volute tongue,and outlet pipeline.An increase in fluid viscosity reduces the turbulent kinetic energy inside the centrifugal pump.Excessive fluid viscosity can lead to difficulties in fluid operation.The increase in fluid viscosity will lead to an increase in the average residence time of particles,an increase in the maximum residence time of particles,and a decrease in the minimum residence time of particles.When the fluid viscosity is 0.1,the maximum retention time of particles continues to increase,and some particles cannot flow out of the centrifugal pump with the fluid and remain inside the pump.