Performance Study Of Oil-gas Two-phase Backflow Pumping Seal

In recent years,with the technological progress and the rotate speed of equipment gradually increasing,oil-gas two phase lubrication technology is more and more common in high-speed conditions,because of its high efficiency,good lubrication,energy consumption and other advantages.But the sealing problem of oil-gas two phase lubrication has become a bottleneck,which restricts its development.Therefore,this paper put forward the oil-gas two-phase backflow pumping seal(OG-BPS)used for oil-gas two-phase operation.The flow field,the temperature field and the deformation of seal end faces were simulated.The theoretical analysis,the experimental research of the steady-state sealing performance and the sealing structure optimization of OG-BPS seal were carried on.On the basis of considering the heat deformation and pressure deformation of seal end faces,the micro-flow field of OG-BPS seal was analyzed by fluid-solid coupling method in Steady-State Thermal,Static Structural and Fluent modules in ANSYS workbench software.The thermal deformation,force deformation,pressure,velocity and phase distribution of flow field of OG-BPS seal were obtained.The deformation of seal end faces is micron level,and the results of fluid-solid coupling are more accurate.OG-BPS seal has a significant dynamic pressure effect,the area between groove area and weir area is full of gas,while the dam area is oil-gas two-phase state,that means OG-BPS seal can achieve oil-free leaks.The temperature field and the deformation of OG-BPS seal end faces under different operating parameters were obtained by comparing and analyzing seal temperature field and the end faces deformation under opening and unopened state.In the opening state,the stress and deformation of seal face are periodically changed with the groove spiral.In the case of unopened state,the contact state of end faces is the divergent gap and the temperature of it is obviously higher than that in opening state.Based on the simulation results of micro-flow field,the effects of different operating parameters(such as rotating speed,pressure difference,liquid-gas ratio and liquid particle size)on the steady-state performance of OG-BPS seal were studied.The law of changes of OG-BPS seal steady-state performance parameters(such as oil-gas two-phase flim opening force,oil-gas two-phase film stiffness,gas-phase suction rate,liquid leakage rate and frictional power consumption)were obtained.The increase of the rotating speed can increase the gas absorption capacity,which makes the seal performance enhanced.When working under negative pressure difference,the liquid-gas ratio has no significant effect on the sealing performance.The influences of different structural parameters(such as groove spiral,groove depth,groove number,groove width ratio and groove dam ratio)on OG-BPS sealing steady-state performance were analyzed and the variation law of sealing steady-state performance parameters was obtained.When the groove spiral ? = 16°?18°,the groove number Ng=12-15,and the groove width ratio?=0.55?0.6 the sealing steady-state performance is optimal.Combined with the results of single parameter analysis,the structure of the seal was analyzed synthetically,and the optimal structure of OG-BPS seal was obtained by orthogonal optimization method,which could be used to guide the engineering design.The seal test bench was designed and manufactured,which was used to test seal.The error between the experimental results of hydrostatic test,variable pressure test,variable rotating speed test,variable lubrication test,dynamic temperature test and the numerical simulation results is less than 10%.The feasibility of the OG-BPS seal and its superior performance in the high-speed oil-gas two-phase condition were verified.This paper provides a design method and theoretical basis for the study of oil-gas two-phase seal by the study of oil-gas two-phase backflow seal,which lays the foundation for the popularization and development of oil-gas two-phase lubrication technology.