| Mixed pump has a wide range of applications in production and life,but with the increase of gas content in fluid medium,the performance and stability of the pump are often greatly compromised.This article takes the "deep-sea air-liquid mixture pump" designed by the National Key Natural Science Research Project as its research object,and conducts numerical analysis on its internal flow state.The outstanding problems in the operation of the internal gas phase distribution and axial force of the mixing pump,The performance change of the mixing pump before and after the balancing hole is opened is studied.The main contents include the following parts:Firstly,using the hybrid model,under the assumption of certain conditions,the internal steady flow of imported gas containing 10%,15%,20%,25%,and 30%of different gas contents was analyzed.It is found that with the increase of imported gas content,the head and efficiency of the mixed-phase pump are decreasing faster and faster.The analysis found that under different conditions of inlet gas content,through the analysis of the surface load of the blades,it was found that the surface pressure of the blades at the same blade height of the same-stage runner continued to decrease as the gas content of the inlet increased.The volume fraction of gas phase has larger values at all levels of wheel hubs,and the accumulation is more obvious in the first stage runners.The liquid velocity at the outlet of the runner is affected by the centrifugal force of the rotor,which is mainly manifested as the circumferential velocity,and the liquid phase velocity at the outlet of the diffuser is mainly based on the axial velocity.The turbulent kinetic energy of the internal flow of the diffuser of the mixing pump was analyzed.It was found that there was a channel vortex near the center of the guide vane flow channel,and the channel vortex intensity increased with the increase of the gas content.Secondly,on the basis of the above studies,the unsteady flow characteristics inside the mixing pump were studied.this paper analyzes the unsteadily calculated pressure pulsations that the pulsation of the impeller and the diffuser increased with the increase of the gas content of the inlet.In addition to obtaining larger pulsation amplitudes on the passing frequency of the runner and the passing frequency of the guide vane,the low-frequency amplitude becomes more and more obvious with the increase of the gas content.Through the analysis of the pressure pulsation probability density map,it is found that the concentration of pressure pulsation energy of each component is different under different gas-bearing conditions.Induced vibration analysis of the infusion pump found that the frequency of vibration in the x and y directions of the runner is twice that of the guide vane.The primary frequency of the vibration in all directions of the diffuser is almost the pass frequency of the rotor blades.With the increase of the GVF,the amplitude of the low frequency vibration in all directions also increases.Finally,aiming at the problem of uneven distribution of gas phase and excessive axial force in the mixing pump,this paper researches and proposes the method of opening the balance hole in the wheel,and analyzes the influence of the impeller balancing hole device on the performance of the mixing pump.By comparison,when the inlet gas content is 10%,20%,and 30%,the axial force of the hybrid pump after opening the balance hole can be reduced by approximately 0.92%,1.23%,and 1.40%,and the efficiency is reduced by approximately 0.90%,1.64%and 2.04%.It is found that when the IGVF is low,the performance of the mixing pump is considered comprehensively.The method of opening the balance hole can reduce the uneven gas distribution in the runner,and can effectively reduce the axial force of the multi-stage pump,and expand the application range of the IGVF of the mixed pump.In order to thoroughly explore the optimal design parameters of the balancing device of the wheel,the influence of the cross-sectional area and the center position of the balance wheel of different wheels on the performance of the pump was analyzed.When d= 1.4mm,the remaining axial force of the pump is approximately 809.27N.When d=3.0mm,the remaining axial force is approximately 794.09N.Comparing the performance of the mixed pump and the axial force when comparing the center position of the balance hole,it is found that the opening of the balanced hole A has less influence on the flow in the runner of the mixing pump,and the resultant force of the axial force of the mixing pump is also the smallest.The frequency of the axial force pulsation of each scheme is the frequency of the mixed-transmission pump,and the pulsation of the axial force of each component of the mixing pump runner is the largest and the internal flow of the runner is the most unstable. |
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