Research On Design And Internal Flow Field Characteristics Of Self-pri Ming Pump In Power Station

As the general centrifugal pump suction level below the impeller,the start must be pre-irrigation,in order to store water in the pump body and the pipeline,the entrance to be installed valves,when the pump work,the valve results in the large hydraulic losses and easy to mix stones,branches and other debris,resulting in tight water sealing and can't fill the water,so that self-priming pump with the emergence and widely used.Self-priming pump has the characteristics of small volume,reliable operation and convenient remote centralized control.In recent years,people have done a lot of theoretical research work on the self-priming pump performance.One is whether the excellent hydraulic performance design is the key factor affecting the self-priming performance.Second,the start-up phase of the self-priming pump is a very turbulent transient gas-liquid two-phase flow process,and the effect of gas-liquid mixing and separation at the start-up stage has a significant effect on the self-priming performance:(1)Systematically elaborated and summarized the research status and development trend of self-priming pump.(2)Based on the summary of the existing design theory of self-priming pump,the design of ZX80-65-178 self-priming centrifugal pump is completed according to the actual needs of power station,which meets the requirements of design parameters and Self-priming performance requirements.(3)The Computational Fluid Dynamics was used to simulate the internal flow of self-priming centrifugal pump.The energy performance,internal flow characteristics and velocity characteristics of the pump under different working conditions were analyzed and studied,check whether the self-priming pump hydraulic design meets the design requirements.(4)The design of the return hole is based on the empirical formula design,it is generally difficult to achieve the optimal design value,for a specific self-priming pump there is an optimal return hole area a nd its installation location,in the initial design Based on the numerical simulation results,the flow characteristics of the return hole are studied and analyzed,and the design of the return hole is redesigned.The change of the area of the return hole and the change of the pressure and the return flow on both sides of the return hole are analyzed.Pump the external characteristics of the change,so as to determine the best area of the return hole.(5)Self-priming pump self-priming process is three-dimensional unsteady turbulence movement,the experiment found that the self-priming pump of the self-priming gas rate has a surge in the process,the maximum can reach half.Therefore,this paper studies the law of gas-liquid two-phase flow in the pump body with different gas-bearing rates by the numerical simulation of gas-liquid two-phase flow theory,which is helpful for studying the flow theory of self-priming pump.(6)This chapter is mainly about unsteady numerical simulation,the main research since the pressure fluctuation changes of suction pump based on hydraulic design,using the research method of the theory of numerical based on struc ture grid large eddy simulation,monitoring the pressure change by setting the important parts of monitoring point in the pump,obtaining the pressure pulse time diagrams of the monitoring points,the frequency diagrams are obtained through the rapid Fourier transform,At the same time,through the analysis of the velocity and pressure cloud.