Study On Multi-objective Optimization Of Hydraulic Performance Of Submersible Sewage Pump Based On Specific Area Control And Genetic Algorithm

Submersible sewage pumps are widely used in many fields such as industrial production,flood control and drainage,and consume a lot of energy.Therefore,higher requirements are placed on the efficiency of the submersible sewage pump.In order to improve the efficiency of the submersible sewage pump and provide an effective reference for the optimal design of the submersible sewage pump,this thesis takes a centrifugal submersible sewage pump with a specific speed of 261 as the research object.The main research contents and conclusions are as follows:1.Study on influence of impeller exit area on centrifugal pump performance.The geometric parameters of the impeller outlet play a key role in the performance of the centrifugal pump.And the impeller outlet diameter,blade outlet degree and impeller outlet width were changed to obtain the influence on impeller efficiency and radial force when keep the volute unchanging.Combined the numerical simulation and engineering experience,the right level number was chosen,and the experimental sample designed by the uniform design experiment method.An approximation model was set about influence of impeller outlet area on impeller efficiency and radial force by using kriging interpolation method.The multi-objective genetic algorithm fitness function is the approximation model set by the kriging model,and it could obtain optimal parameters.And then the optimal parameters should be verified by the numerical simulation method and analyzed the result.The result shows that the area ratio has a important influence on the radial force.Radial force increases first and then decreases as the area ratio increases.The radial force should reach the minimum when the area ratio reaches 1.2~1.4.And the influence of the area ratio on efficiency is increased first and then decrease.When the area ratio reaches 1.0~1.2,the efficiency has been reached the maximum.The volute wrap angle has so little effect on the efficiency that it can be ignorant.When the wrap angle is 9 degrees,the radial force is reached the minimum?2.Study on the influence of volute area and tongue angle on the performance of centrifugal pump.The performance of a centrifugal pump is influenced by many parameters,and the effect is nonlinear,and it is difficult to obtain an accurate analytical equation.Therefore,using the proxy model to obtain an approximate mathematical model between the performance of the centrifugal pump and the area ratio,and then using the genetic algorithm to find the optimal parameter solution.Keep the structure of the impeller unchanging,by adjusting the size of the volute tongue angle and the eighth cross-sectional area ratio.Combine numerical simulation with engineering experience to select the appropriate number of factors.The experimental sample was designed by the uniform design experiment method,and the approximate function model of the efficiency of the volute tongue angle and area comparison was established by artificial neural network.The approximation function is taken as a fitness function into the genetic algorithm,and the most parameters are obtained,and the results are analyzed by numerical simulation.The results show that the effect of area ratio and placement angle on the performance of the centrifugal pump is coupled,not a fixed set of values.The tongue placement angle is optimally between 42 degrees and 44 degrees with an area ratio between 1 and 1.2.As the angle at which the tongue is placed increases,the area decreases;as the angle at which the tongue is placed decreases,the area ratio increases.At this point,the efficiency of the centrifugal pump is basically unchanged.3.Research on optimization of unsteady performance of impeller and voluteThe unsteady performance of the impeller and the volute is also part of the overall performance of the pump.The pressure pulsation and radial force caused by the rotatorstator interaction between the volute and the impeller will greatly affect the stability and safety of the centrifugal pump.Therefore,numerical simulation experiments are performed on the model before and after optimization,and the radial force and pressure pulsation under unsteady conditions are compared.Through the analysis of the results,it can be seen that a relatively good optimization effect has been achieved in the scheme optimized for the radial force,and the radial force is much reduced compared to the original scheme.It is consistent,indicating that the main parameter that causes the change of the impeller is the number of blades,and the frequency of the radial force is an integer multiple of the blade frequency,and is mainly based on the frequency of the blades passing.For the optimization of the volute,the pressure pulsation coefficient of the volute after the optimization is reduced in both the reverse radial direction and the axial direction.Compared with the original solution,the pressure pulsation coefficient of the optimized solution of the volute is more axially changed than the radial direction.Change is small.The main frequency and secondary frequency of the pressure pulsation coefficient before and after optimization are unchanged,and they are still integer multiples of the leaf frequency.Changing the volute will not change the frequency of the pressure.