| With the rapid development of industrial technology,the ecological environment in which people live is facing increasingly severe challenges.In order to better fight the battle against pollution,many researchers have begun to focus on equipment that uses clean energy.As one of the most widely used cleaning and cooling equipment,steam jet pump is widely used in various fields due to its long service life and low maintenance cost,but the promotion is limited by its low work efficiency.Therefore,improving the working efficiency of steam jet pump has an extraordinary significance for its application and promotion of ecological civilization.As the most important part of the steam jet pump,the ejector is the main way to improve the efficiency of the jet pump.With the rapid development of computer simulation calculations,Computational Fluid Dynamics(CFD)and the optimized design module Workbench DesignXplorer have become the main means to optimize the structure of the ejector.Combining the two to study the structure optimization of the ejector,not only reduces the research cost,improve research efficiency,and make up for the limitations of single parameter analysis and improve the accuracy of optimization results,and provide ideas and reference value for the optimal design and performance research of ejectors.A combination of CFD and Workbench DesignXplorer was used in this paper.Based on the single parameter analysis,the effects of various geometric parameters(contraction angle A1,throat diameter D,nozzle exit position NXP and diffusion angle A2)on the jet pump’s entrainment ratio and the capability to resist back pressure were studied.The optimal structure under single parameter analysis and the appropriate range of variation of each geometric parameter were obtained,and a new method for judging the capability was proposed.It defined per unit volume fluid kinetic energy as eki at the exit of ejector throat,and evaluated the capability by ek1.The optimal structure of the ejector was obtained based on multi-parameter analysis,and it was compared with the original structure and the optimal structure obtained by single parameter analysis.The advantages of multi-parameter analysis were highlighted and the synergistic effect between the geometric parameters of the ejector was proved.At the same time,the sensitivity analysis of the four geometric parameters for the jet pump’s entrainment ratio and capability to resist back pressure was carried out.The effects of operating parameters(working steam pressure and secondary fluid pressure)on the optimal structure of the ejector were studied,and the correlation analysis of each geometric parameter in the comprehensive performance(entrainment ratio and the capability to resist back pressure)of the jet pump was carried out.The results show that the optimal structure of the ejector under specific operating parameters is obtained by single parameter analysis:A1=A2=2°,D=28mm,NXP=0mm.The optimal structure of the ejector after multi-parameter analysis is:A1=A2=2°,D=30mm,NXP=-10mm,and its entrainment ratio is improved by 14.6%compared to the optimal solution for single parameter analysis.ek1 can be used as a criterion for judging the capability to resist back pressure of the jet pump.The larger the ek1,the stronger the capability is.When the pressure of the working steam or secondary fluid is increased,D and NXP can be appropriately increased to enhance the overall performance of the pump.The optimal solution for A1 and A2 does not change with the change of the pressure of the working steam or secondary fluid,and the optimal solution for both is always 2°.In terms of the entrainment ratio,only A1 has a correlation with NXP,and there is no correlation between other geometric parameters.There is no correlation between A1,A2 and NXP in terms of the capability to resist back pressure. |
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