Optimization Design Of Liquid Ring Vacuum Pump Based On Orthogonal Test And CFD

Liquid ring vacuum pump is a kind of special pump commonly used in industrial production.Due to its internal unsteady,swirl,gas-liquid two-phase flow,compressible,recirculation and other complex flow phenomena,its pump performance is poor,so all along,How to improve the performance of the liquid ring vacuum pump,optimize its design and analysis,and ensure its long-term reliable operation is an important subject.In this paper,the main researches are carried out on the impeller and the suction port of the liquid ring vacuum pump.On the one hand,the orthogonal design method is used to optimize the design of the impeller,and on the other hand,the shape of the suction port is improved according to the inlet recirculation phenomenon of the suction port.The numerical research and experimental research are used to study and analyze the contents of these two aspects.The main work and conclusions are as follows:1.The numerical simulation of the whole flow passage of the liquid ring vacuum pump is carried out.The numerical simulation of the imported vacuum is compared with the experimentally measured results,it is found that the trend of the two is more consistent.Therefore,the numerical simulation method can be used to predict the performance of the liquid ring vacuum pump reliably.2.Firstly,the sensitivity analysis of many geometric parameters of the liquid ring vacuum pump impeller is carried out,and the four geometric parameters of the hub ratio,eccentricity,number of blades and blade placement angle which have great influence on the inlet vacuum level are selected as the experimental factors of the orthogonal test.Then according to the orthogonal test principle,the experimental scheme design is carried out.The inlet vacuum level and the shaft power are used as the evaluation indicators.The numerical calculation results of the orthogonal experimental design scheme are sequentially subjected to visual analysis,range analysis and variance analysis,and the analysis results are comprehensively determined.The optimization scheme has a hub ratio of 0.4,an eccentricity of 16 mm,a number of blades of 14,and a blade placement angle of 50°.Finally,the numerical calculation results of the model before and after optimization are compared.it is found that under the rated working condition,the inlet vacuum of the optimized model is 2.38 kPa higher than that before optimization,while the optimized shaft power is reduced by 0.06 kW,and the internal flow state is also improved.It shows that the optimization design of the liquid ring vacuum pump impeller can be realized by using the orthogonal experimental design method combined with numerical simulation.3.Through the research on the inlet recirculation phenomenon of the suction port of the liquid ring vacuum pump,it is found that the inlet recirculation phenomenon of the suction port of the liquid ring vacuum pump occurs under various working conditions,but the recirculation intensity and the position where the recirculation occurs are different.Under the condition of small flow rate,the recirculation mainly occurs at the upper end of the suction inlet,and the recirculation intensity is large.With the increase of flow rate,the recirculation at the upper end of the suction inlet decreases,but the recirculation at the lower end of the suction inlet increases gradually.At the condition of large flow rate,the recirculation occurs at the lower end of the suction inlet,and the recirculation strength is weaker than the recirculation intensity at the upper end of the suction port at a small flow rate.In the process of running under various working conditions,the gas flow in the middle of the suction port is less affected by the recirculation.Based on the analysis of the pressure distribution at the suction port,it is found that the reason for the recirculation of the suction port is that the pressure in the suction section is lower than the pressure of the suction zone in the corresponding impeller.According to the recirculation phenomenon of the suction port,the shape of the suction port is improved based on the basis.The numerical calculation results of the improved scheme are analyzed.The results show that,under the premise of ensuring the same suction port area,according to the operation requirements of the liquid ring vacuum pump,the starting angle and the end angle of the suction port are appropriately adjusted.It can improve the recirculation of the suction port and improve the performance of the pump to a certain extent.