Research On Large Particle Wear Mechanism In A Solid-liquid Two-phase Pump

One kind of the widely-used pumps is solid-liquid two-phase centrifugal pump,which is the key equipment in transport of solid-liquid mixture.It is mainly used in water supply,sewage treatment,agricultural irrigation,petroleum industry,metallurgy industry,marine mining,thermal power,urban infrastructure and other industries.However,due to the large amount of solid particles in the transport mixture,the particles impact the inner wall of the pump during the liquid transport process,not only causing damage to the overcurrent components,but also affecting the operation of the centrifugal pump.The unstable equipment will cause low-efficiency and high-repair-cost.In order to solve the corresponding problems,domestic and foreign scholars have carried out a lot of research,and many valuable theories are achieved.But most of the proposed design schemes are based on experience,which means locking summary of the internal flow mechanism of the two-phase pump,for the diverse parameters of particles and the complex structure of the pump.Therefore,it is of great significance for the design of the solid-liquid two-phase pump to study the internal flow mechanism and wear mechanism.In this paper,a centrifugal pump with a specific speed of 102 is studied.In order to analyze the internal flow characteristics of the centrifugal pump and the wear of the overcurrent components when the pump convey mixture with large particles,we carry out numerical simulation of centrifugal pump with different mass concentrations under rated condition and the experiments under same situations to verify the accuracy.We use EDEM-FLUENT coupling calculation to research the flow in the two-phase pump.The RNG k-? turbulence model is used to calculate the flow field of solid-liquid two-phase flow,the flow characteristics of the internal flow field of the centrifugal pump and the wear of the components are analyzed.The main contents of the dissertation are as follows:1.A solid-liquid two-phase flow test rig is built to study the relationship between the hydraulic performance and wear condition of the centrifugal pump under the rated working condition with the mass concentration ranging from 1% to 10%.We obtain the results that different concentrations of the particle can influent the head to varying degree,beside the primary wear appear at the suction side of the impeller,the front shroud and the back shroud.2.A hydraulic model of the centrifugal pump is finished by the 3D software UG,and meshed by the professional meshing software ICEM.Finally,we use the CFD software Fluent to carry out Steady simulation when the pump supply water and mixture,and compare the performance parameters of the simulated centrifugal pump with the test to verify the reliability of the calculation model.At last,we can get the relationship between the external characteristics of the pump with the flow characteristics of the internal flow field.Not only the validity of the numerical simulation is verified,but also we can conclude that the presence of particles lead to the turbulent internal flow field.3.In order to study the wear of the solid particle mass concentration on the centrifugal pump over-current components,the coupling of Fluent and EDEM was used to study the over-flow of solid particles to the centrifugal pump at particle mass concentrations.The wear of the parts is compared with the test results to analysis how the internal influence the wear.It is found that the impeller suffer the collisions twice in one cycle,and the more particles in the flow field the more serious wear is.