Research On Internal Flow And Energy Conversion Characteristics Within The Impeller Region In Multiphase Pump

Multiphase pump is one of the main equipments for the exploitation of marine mineral resources.It has an important position in the field of deep sea resource exploitation.Since the last century,many foreign scientific research institutions have begun to research on the multiphase technology,and gradually mature.The products are applied to the actual exploitation of marine resources,while the research on domestic multiphase technology is relatively backward.Many technologies still need to be improved,and they are generally lagging behind.One of the key issues for the research on multiphase technology is to develop multiphase pump.Multiphase pump can improve the mining efficiency of deep sea mineral resources and reduce the mining cost.It has an irreplaceable role in the development of marine mineral resources,therefore,research on multiphase pump is crucial.In the actual operation of multiphase pump,the multiphase pump has lower hydraulic efficiency and poor energy conversion capacity under the gas-containing conditions,at present,the research on the energy conversion characteristics of multiphase mixed pump has not been reported in related literatures yet.Based on this,this paper studies the internal flow mechanism of multiphase pump,the distribution of pressure load of multiphase pump is analyzed under the different fluid mediums(pure water medium and gas-liquid two-phase medium),and the energy conversion characteristics of the impeller region are studied.Through the above research,the following conclusions are drawn:(1)Analysis of internal flow mechanism of multiphase pump under different mediumsThe numerical simulation method was used to research the multiphase pump under the different medium conditions.It were analyzed the effects of flow rate and gas content on the external characteristics of multiphase mixed pump and the internal flow characteristics of the flow components,and obtained the external characteristic curves and flow field distribution of multiphase mixed pump under different media conditions.It is found that the the influence of gas content on the external characteristics of the multiphase pump under low flow conditions is significantly less than that of large flow conditions under the gas-liquid two-phase medium.The external characteristics of the pump are significantly less than the large flow conditions;the increase of the flow rate and the increase of the gas content have a certain improvement for the low pressure region at the inlet of the impeller of the multiphase pump,and with the increase of the gas content,the impeller suction surface begins to gradually accumulate in the gas phase,and the gas phase accumulation region begins to gradually de-flow under the large flow condition.(2)Distribution of pressure load of multiphase pump under different mediumsBy extracting the static pressure of the blade surface at different blade heights of the impeller blades,the multiphase pump under different medium conditions was studied.The static pressure distribution and pressure load distribution of the blade surface were analyzed.The static pressure distribution curve and pressure load distribution curve of the multiphase pump at different flow rates and different gas contents are obtained.Under the pure water medium,with the increase of flow rate,the work capacity at the hub begins to increase,while the work capacity at the shroud begins to decrease gradually,and the high efficiency area of impeller works gradually moves towards the outlet,and the negative power area at the inlet increases;Under the condition of gas-liquid two-phase medium,the static pressure of the working surface of blade in the multiphase pump is less affected by the gas content,and under the large flow condition,the static pressure of the suction surface is affected by the gas containing area is larger than the small flow condition;Under the same flow rate,with the increase of the inlet gas content,The work capacity of the multiphase pump impeller to the fluid medium is gradually decreasing,and the high efficiency region of the multiphase pump begins to move toward the impeller outlet.(3)Study on energy conversion characteristics of multiphase pump impeller under different mediumsBy extracting the multiphase pump impeller hub and the rim speed parameters under the pure water medium and the gas-liquid two-phase medium,combined with the blade-type fluid mechanical Euler equation,and the energy transfer performance of the multiphase pump impeller is analyzed.It was found that the impeller working surface has a higher energy transfer quality in the range of 0°~60° under the pure water medium and the gas-liquid two-phase medium,and after the wrap angle is greater than 60°,energy transfer performance begins to deteriorate,the energy transfer is unstable;but the impeller suction surface is reversed,The energy transfer performance is poor in the range of 0° to 60°,while the energy transfer performance is excellent after the wrap angle is greater than 60°,which indicates that the energy transfer performance of the working surface of the impeller multiphase pump is opposite to that of the suction surface,and the energy transfer quality of the impeller working surface is worse than that of the impeller suction surface;Because of the flow separation occurs in the impeller region under gas-liquid two-phase medium,which makes the hydraulic loss more than the pure water condition.Therefore,it can be seen that the energy transfer performance of the multiphase pump impeller region is lower than that of the pure water medium under the gas-liquid two-phase condition.