Study On The Sealing Performance Of Variable Cross Section Sealing Ring Considering The Effect Of Temperature

The variable cross section sealing ring has excellent sealing performance due to its special lubrication boundary structure,and is widely used in harsh sealing conditions such as high temperature,high pressure,and high speed.During operation,variable cross section sealing ring can experience a lag in the lubricant,resulting in an increase in temperature between the dynamic sealing surfaces.Temperature changes can alter the physical properties of the elastic material and lubricating oil,accelerating the aging and failure of the seal,and even causing safety accidents in severe cases.Currently,research on variable cross section sealing ring is still focused on the sealing mechanism and structural parameters,and there has been no research on the effect of temperature on their sealing performance.To address this weakness and improve the performance and service life of variable cross section sealing ring,this paper focuses on the lubricating oil film during stable operation of the seal,and uses a research method that combines finite element simulation and theoretical formula calculation to study the effect of temperature on the sealing performance of the seal.A finite element simulation model of a lubricating oil film with fixed thickness was established to calculate the effects of different operating parameters on the temperature field distribution,maximum temperature,maximum pressure,and leakage of the oil film.Using the temperature value as a criterion,the applicable operating range of three viscosity grades of polyα-alphaolefin synthetic liquid lubricating oil was explored.Additionally,a thermal fluid lubrication numerical calculation method considering viscosity-temperature characteristics was established to perform iterative calculations of the Reynolds equation and energy equation.The accuracy of the finite element simulation results was verified using theoretical formula calculations.The study shows that the high-temperature range of the oil film expands with increasing rotational speed,and shrinks with increasing sealing pressure,and also decreases with an increase in lubricant temperature.With increasing speed,the maximum temperature,maximum pressure,and leakage of the oil film all increase.With increasing sealing pressure,the maximum pressure and leakage of the oil film increase,and the maximum temperature of the oil film decreases.With increasing lubricating oil temperature,the maximum temperature of the ISO150 viscosity lubricating oil film shows a trend of first decreasing and then increasing,the maximum temperature of the ISO220 viscosity lubricating oil film decreases,and the maximum temperature of the ISO320 viscosity lubricating oil film shows a pattern of decrease-increase-decrease.The analytical solution is slightly larger than the simulation result,but the difference between the two is less than 5%.When three different viscosity lubricating oils are used for seals with variable cross sections,in order to provide good long-term service life and sealing performance,the sealing pressure should be higher than 1MPa,and the lubricating oil temperature should be higher than 313 K.For ISO150 viscosity lubricating oil,the speed should be lower than 4000 rpm,for ISO220 viscosity lubricating oil,the speed should be lower than 2800 rpm and for ISO320 viscosity lubricating oil,the speed should be lower than 2500 rpm.Based on the finite element simulation of lubricating oil film with fixed thickness,a lubricating oil film model with variable thickness was established for the actual service of variable cross section sealing ring.The effect of changing film thickness on temperature field and sealing performance was studied.The accuracy of the results was verified by using the established thermal fluid lubrication theory formula for calculation.The research results show that the temperature field of the lubricating oil film with variable thickness changes with the parameters of each working condition in accordance with the conclusion of the lubricating oil film with fixed thickness.However,the diffusion and shrinkage rate of the temperature field is slower and there is a curve in the temperature contour near the trough of the lubrication boundary.The variation law of the highest temperature,maximum pressure and leakage of the oil film with variable thickness with the change of speed and seal pressure is the same as that of the lubricating oil film with fixed thickness,while the highest temperature of the oil film presents a decreasing and then increasing trend with the increase of lubricating oil temperature,the maximum pressure of the oil film decreases and the leakage increases accordingly.The theoretical formula calculation results have an error of less than 5%compared with the simulation results.Compared with the fixed film thickness,the variable thickness reduces the highest temperature value and the maximum pressure value of the oil film,expands the scope of application of the variable cross section sealing ring and lubricating oil in the appropriate working conditions,but increases the leakage value.