Research On Transient Self-priming Characteristics And Flow Law Of External Mixing Centrifugal Pump

As a special type of centrifugal pump,external mixing centrifugal pump which water does not need to be injected into before starting,can suck up the water by running through a short time and be put into normal operation,depending on the special structure of the pump with itself.The self-priming process of external mixing centrifugal pump can be defined as the process from the pump start to normal operation.During the self-priming process,complex gas-liquid two phase flow,including interaction between air and water,occurs in pump.Research on the self-priming process focuses on the distribution of air-water two phase and the flow law of air-water in pump.The aim of research on the self-priming process of external mixing centrifugal pump was to reveal the spatiotemporal characteristics of gas-liquid mixed flow structure and to obtain the characteristics of gas-liquid mixed flow and the evolution process with time.It can provide theoretical support for further research on the self-priming performance and design and optimization of external mixing centrifugal pump.The main work and results of the study are as follows:1.A numerical analysis model was established.Corresponding two-dimensional drawing and geometric parameters were obtained by performing hydraulic design calculations for 65zw30-40 external mixing centrifugal pump.Based on this,three-dimensional model was built with CATIA and the grid was divided with ICEM,then the grids were imported into Fluent to solve operation.2.Self-priming characteristics of external mixing centrifugal pump was researched.Based on k-?turbulence model and Mixture multiphase flow model,the whole self-priming process of pump was studied,which can be divided into three stage:self-priming initial stage?0-30s?,stable self-priming process?30-140s?and self-priming last stage?140-160s?.3.The influence of reflux hole area on the self-priming characteristics was researched.There were four different schemes(A_H=114.26mm^2?A_H=178.54mm²?A_H=257.1mm²?A_H=349.94mm²)formulated to study on the influence of reflux hole on the self-priming characteristics.The result was that when A_H equals 257.1mm²,the self-priming characteristics of pump was optimum.4.The effect of liquid storage of pump on the self-priming characteristics was researched.The initial liquid level height was introduced to study the influence of liquid storage of pump on the self-priming characteristics.Three different schemes of liquid level height?h _L=120mm?h_L=130mm?h_L=140mm?were selected and h_L=130mm was the best scheme,when the self-priming characteristics was optimum.5.Experiment research.The performance of centrifugal pump was studied by adopting experiment method.The reliability of numerical results was confirmed by comparing the experiment data with the numerical calculation results.By experiment research,taking self-priming time and efficiency of pump into consideration,A_H=257.1mm² was the optimum reflux hole scheme.