Research On Gas-liquid Mixing And Separation And Performance Optimization Of Power Station Self-priming Pump

With the self-priming pump widely used in the field of agriculture and industry,some hydropower stations also gradually adopts self-priming pump instead of submerged pump for the sake of the reliability and maintenance convenience.In recent years,the safety and stability of self-priming pump is a hot topic and the important direction in research of water pump,not only hydraulic performance but also the self-priming time and self-priming height have become the key measure.the starting-up phase of self-priming pump is a more complex problem about unsteady gas-liquid two-phase flow, the gas-liquid mixing and separation of good or bad will directly affect the self-priming time and self-priming height, in some time, self-priming time and self-priming height are the key indicators of mesuring self-priming pump performance. So in order to improve the self-priming performance of self-priming pump,it is the key to figure out the unsteady gas-liquid two phase flow problem of self-priming pump in starting-up process.In this paper,I have mainly self-priming pump model with named ZX80 changed on the basis of the existing self-priming pump design theory;The remodel was proved to be rational and feasible through the comparison for the hydraulic performance and internal flow condition before and after modification.In the meantime, the unsteady gas-liquid two phase flow problem of the remodel of the outer recirculation self-priming pump in the self-priming process have been researched.The main work and research results are as follows.Choosing outer recirculation self-priming pump named ZX80 as the research object of this paper.Because of the lacking of parts of the original Hydraulic drawings,taking advantage of the rest and combinating of self-priming pump design theory to design the pumpSeting up the physical models about before and after modification of ZX80 external mixing self-priming pump, meshing separately at the same time, then, though the RANS simulation method and the standard k-ε turbulence model which is double-equation, these pumps has separately been done steady numerical simulation in five working flow points.On the basis of the results of steady numerical simulation, having separately given the contrast analysis of the competitiveness of the external characteristic and the internal flow field about the external mixed self-priming pumps, respectively. On the one hand, the Q-H curve and the Q-P curve,the Q-η curve are compared,which sees that the head and efficiency have been improved and shaft power have been reduced when the gas-liquid separation chamber changed. On the other hand, with the streamline and turbulent kinetic energy dissipation rate of the gas-liquid separation chamber of the pumps analyzed, the results show that the streamline of gas-liquid separation chamber more smooth and its disorder degree reduced, efficiency improved after modification.Obviously, the modification of for the separation chamber is successful in this paper, not only ZX80 pump lift and efficiency increased, but also the disorder of gas-liquid separation chamber vortex state distribution improved.Based on the theoretical basis of multiphase flow, the start-up process of the external mixed self-priming pump named ZX80 that has been changed. Setting imported boundary conditions for speed, in order to make simulating speed changes closer to the actual situation,the speed change program have been imported the UDF of the Fluent software by the use of C language programming, studying gas liquid two phase flow in the start process of pump and describing the flow structure evolution of self-priming pump.