Study On Energy Conversion Characteristics Of Multiphase Pump Under Multiple Working Conditions

As a source of power for the development of modern science and technology,energy promotes the progress of human civilization.With the expansion of the field of energy exploitation,human eyes are gradually shifting to the oil and gas rich ocean.Therefore,under the development,research and experimental demonstration of experts and scholars all over the world,a kind of multiphase pump as the "heart" of the multiphase mixed transport technology emerges.Its stable and efficient operation is the top priority of offshore oil and gas exploitation.Tip clearance is an essential structure in multiphase pump,and the tip leakage eddy will lead to the deterioration of pump performance.However,at present,there is a lack of research on the energy conversion and energy loss of multiphase pump with different tip clearance,and few articles have explored the energy conversion characteristics of multiphase pump under the energy transport theory.Therefore,in order to reveal the energy conversion rule in the multiphase pump under different tip clearance,this paper will conduct a systematic study on the energy conversion and energy loss of the multiphase pump.(1)The influence of gas content and flow rate under different tip clearance on the boosting performance of the multiphase pump was explored by studying the relative velocity variation law of the axial direction of the blade and the static pressure distribution of the blade under multiple working conditions.Meanwhile,the dynamic head,static head,power variation and energy density distribution of various sections of the multiphase pump were analyzed.The influence law of tip clearance on energy conversion of multiphase pump is revealed.The results show that both flow rate and gas content can reduce the supercharging performance of the pump,and the 1.5mm tip clearance is beneficial to restrain the energy loss at the clearance.(2)Applying the energy transport theory,the energy exchange characteristics of the multiphase pump under multiple working conditions were further studied,and the influences of pressure gradient,rotation effect and viscous dissipation on the energy conversion of the multiphase pump were summarized.The analysis shows that the work performance of pressure gradient is improved with the increase of tip clearance under variable flow conditions,and the change rule is opposite when there is a gas phase in the impeller,Lamb vector divergence has a "sandwich three-layer" structure under multiple working conditions,and the fluid momentum transfer becomes more obvious with the increase of clearance size.The variation law of vortex pseudo energy dissipation in the impeller under different tip clearance conditions is relatively chaotic.In general,the energy dissipation in the impeller under the condition of gas content is relatively large.Therefore,the energy loss in the multiphase pump will be further analyzed.(3)The turbulent dissipation distribution law in the booster unit is discussed because of the non-negligible energy loss in the energy conversion process.The energy dissipation characteristics of the multiphase pump under different tip clearance are expounded through the entropy production theory,and the energy loss caused by tip clearance to themultiphase pump is quantitatively analyzed.The results show that the tip clearance is in direct proportion to the energy dissipation of the impeller.However,the presence of the gas phase will disturb the energy dissipation distribution law of the impeller under different tip clearance,and the entropy production of the impeller wall is mainly distributed in the pressure surface of the blade,tip clearance,leading edge of the blade inlet and near the inlet hub.In addition,the increase of tip clearance is conducive to reducing the friction loss of the impeller blade,and clearance size is not the only indicator to measure tip clearance loss.Under different flow rates and different gas content conditions,the turbulent dissipation loss in the impeller is less affected by tip clearance,and the variation law of blade load loss is more complex under multiple working conditions...