Multi-field Coupling Study On Rigid-flexible Helical Surface Between Rigid And Flexible In Progressing Cavity Pumps

Progressing Cavity Pumps is an emerging artificial lift equipment.The application of PCP has many limitations,how to improve the efficiency and lifting capacity of PCP is an urgent technical problem.Supported by the National Natural Science Foundation of China(11502051),the dynamic research on the periodic contact and division of the rigid-flexible helical surface of screw pump was carried out.The temperature gradient regularity of the stator under multi-field coupling is the research emphasis,change the correlation parameters of the screw pump model and analyze the influence of each parameter on the stator deformation and temperature gradient of the screw pump.According to the profile equation of single screw pump,the three-dimensional model of single screw pump with different structure parameters is constructed.ICEM CFD software was used to parameterize the three-dimensional model and obtain the hexahedron element.Analyzing the kinematics of single screw pump and considering the nonlinear of double material,the three-dimensional finite element analysis model of PCP was established through contact with the creation and boundary conditions.With the decrease of the size of the element and the increase of the interference between the stator and the rotor,the stator deformation is increasing continuously,the element size and the interference of single screw pump finite element model was determined.From the perspective of spatial position,the inner surface of the stator at the position where the rotor’s load is applied has the maximum deformation,the maximum stress of the semi-circular contact zone of the stator,and the maximum contact pressure of the lateral contact zone of the stator;from the perspective of time history,the inner surface of the stator is most deformed in contact with the rotor at the next moment.During the process of rotor rotation,stator linear segment has large deformation and long duration,the interaction of the semicircle is greater and the change is more intense.Compared to the screw pump,the stator of ISO-wall thickness has smaller deformation,the interaction force between stator and rotor in ISO-wall thickness is more balanced,the deformation response velocity of stator in ISO-wall thickness is faster.With the effect of multi-field coupling,interference,friction coefficient,loss factor and rotation rate affect the temperature field of stator.In extreme conditions,the critical value of interference in conventional screw is 0.27 mm,the critical value of interference in ISO-wall thickness is 0.276mm;the critical value of friction coefficient in conventional screw is 0.55,the critical value of friction coefficient in ISO-wall thickness is 0.528.Interference,friction coefficient,and rotation rate influence hysteresis thermogenous together.The screw pump works normally when interference is 0.5mm and loss factor is less than 0.5 or interference is less than 0.5mm;under extreme conditions,preventing the stator from burning out,a higher critical point of screw speed can be obtained by using stator rubber with lower loss factor.