高速转轴密封微间隙润滑气膜形成与影响因素研究

Study on Formation and Influencing Factors of Lubricating Gas Film in Micro-gap of High-speed Rotating Shaft Seal

以天然气井高压旋转控制头为工程背景,利用流体动压机理,针对高转速轴密封问题,提出通过在密封橡胶与轴微间隙接触界面建立润滑气膜,以有效解决橡胶干摩擦失效问题。在胶芯内壁构建螺旋槽,改变柱状摩擦副接触面结构,以产生气体动压效应。通过建立柱面微间隙气膜模型,实现了气膜流场数值模拟,并验证了螺旋槽结构参数、转速变化等因素对气膜的影响规律。结果表明:偏心率是润滑气膜形成的必要条件;在偏心率和转速一定的条件下,螺旋槽与轴转动方向相反且旋向为50°时,气膜压力最大,可获得最佳气体动压效应。

Based on the engineering background of high-pressure rotating control head of natural gas well and making use of fluid dynamic pressure mechanism,the method to solve dry friction failure of rubber by establishing a lubricating gas film at the contact interface between sealing rubber and shaft was proposed so that high-speed rotating shaft can be sealed well,in which,a spiral groove was constructed on inner wall of the rubber core,and contact surface structure of the cylindrical friction pair was changed to produce gas dynamic pressure effect.Through setting up gas film model of the cylindrical micro-gap,the numerical simulation of gas film flow field was realized and the influence law of both spiral groove structure parameters and speed variation on the gas film were verified.The results showed that,the eccentricity is a necessary condition for formation of the lubricating gas film;and under certain conditions of eccentricity and rotation speed,when the spiral groove rotates in an opposite direction to the axis and the rotation direction is 50°,the gas film pressure reaches the maximum,and the optimal gas dynamic pressure effect can be obtained.