Study On Lubrication Mechanism Of Air Film In Micro-clearance Of Rotary Shaft Seal

Rotary shaft seal is widely used in petroleum and petrochemical,aerospace,national defense,machine tool industry and other fields.Under high speed condition,dry friction between seal rubber and high speed shaft will accelerate rubber wear and lead to seal failure.Based on the high pressure rotating control head of natural gas well as the mechanism of fluid dynamic pressure,aiming at the problem of high-speed shaft sealing,this paper puts forward that the problem of rubber dry friction failure can be effectively solved by establishing lubricating gas film at the interface between sealing rubber and shaft micro gap.In this paper,aiming at the dry friction phenomenon of micro clearance between the rotating shaft and the sealing rubber,the generating conditions of the cylinder gas film are analyzed theoretically,and the cylinder gas film simulation model is established.According to the characteristics of the cylinder gas film seal,through the CFD numerical simulation method,taking Solid Works and ICEM as the simulation platform,proposing the block gas film structure grid division method,obtaining the internal relations of leakage,buoyancy and friction torque.Through the establishment of four different cylinder gas film models,the maximum gas film pressure produced under the same working condition is analyzed,and the conclusion is: under the working condition,the existence of eccentric clearance between the seal rubber and the shaft assembly is the necessary condition to produce gas film pressure;the spiral groove of the friction surface between the seal rubber and the shaft is the necessary condition to enhance the gas film pressure.In this paper,the problem of friction and wear between the sealing rubber and the shaft is effectively improved by means of the design of spiral groove structure and the method of changing the state of contact surface.At the same time,through the study of the relationship between the spiral groove direction and the shaft direction,it is concluded that the lubrication and sealing performance are better when the spiral groove direction is opposite to the shaft direction.This paper proves the feasibility of rubber film lubrication of high-speed shaft seal,and the research is of great significance to enrich the theory of gas seal rubber film lubrication of high-speed shaft.