Research On The Prediction Method Of Dynamic Leakage Of All Metal Single Screw Pump

The stator and rotor are made of metal materials in all metal single screw pump,it has the advantages of high temperature resistance,wear resistance and corrosion resistance,and there are obvious advantages in production wells with higher formation temperature and heavy oil wells.But the clearance fit between stator and rotor also brings new production problems.,fixed leakage phenomenon exists in the working process due to the fit clearance,and the leakage will affect the volume efficiency and lifting performance of the pump.Therefore,the calculation of leakage is of great significance for improving the performance of all-metal single screw pump.In this paper,the motion law and dynamic characteristics of all-metal single screw pump rotor are summarized and analyzed,the internal leakage mechanism of the pump is analyzed and discussed,and simplified the clearance structure of the transverse and longitudinal leakage directions.The effect of cavitation on the lifting process of low viscosity fluid is discussed by a simplified model,improved the influence of fluid viscosity on lifting efficiency of all-metal single screw pump.and a calculation model of leakage between chambers of all-metal single screw pump is established based on the theory of gap flow.The geometric model of the computational domain of the fluid in the pump for numerical simulation was established by Solid Works.The optimal meshing strategy is selected by comparing different meshing methods,and then established the finite element model for numerical simulation.CFD software was used to simulate the flow field of all-metal single screw pump,the characteristics of pressure field and velocity field inside the pump are analyzed.Then discussed the effects of clearance height,rotor speed and fluid viscosity on leakage under dynamic conditions.Because of the special structure of the pump,it is difficult to calculate the clearance size of the leakage calculation model due to the change of the clearance size at all times,dimensionless clearance parameters are defined for this problem,the calculation method of clearance parameters is obtained by fitting a large number of simulation results.The leakage calculation model is further improved and the leakage prediction calculation under dynamic conditions is realized.