椭圆微织构结构参数对气膜浮环密封性能的影响

Effect of Elliptical Micro-textured Structure Parameters on Sealing Performance of Floating Ring with Gas Film

目的提高以气体作为润滑介质的织构化浮环密封的密封性能,为气膜浮环密封的优化设计提供理论基础。方法基于气体润滑理论,建立了表征织构化密封环间隙气体流动状态的物理方程,采用有限差分法对控制方程进行数值求解,以气膜浮升力最大和泄漏率最小为优选目标,分析特定工况条件下椭圆微织构孔结构参数对密封性能的影响规律,获得密封性能优良的结构参数的优选范围。结果随着转速和压力的提高均可增强动压效应,提高气膜浮升力。泄漏率随着压力的增加显著升高,但随着转速的提高缓慢下降。椭圆微织构孔几何结构参数对浮环密封气膜浮升力数值的影响因素主次顺序为:面积率>形状比>织构深度>旋转倾角。对密封装置的泄漏率数值的影响因素主次顺序为:织构深度>形状比>面积率>旋转倾角。在转速和压力分析范围内,浮环密封的润滑与密封性能受轴套表面织构几何参数的影响,推荐优先选择的椭圆织构结构参数为:形状比γ=3∶1,面积率Sp=11%,旋转倾角β=0°和织构深度ht=1μm,以获得良好的密封性能。结论微织构的存在可以改善浮环密封的密封性能,选择合适的表面织构参数能起到减摩润滑的效果。研究结果可为气膜浮环密封的加工制造提供理论参考。

To improve the sealing performance of the micro-textured floating ring seal with gas as the lubricating medium,the effect of elliptical micro-textured holes on the hydrodynamic lubrication of the floating ring gas film seal was studied under different working parameters to provide the theory for the optimal design of the floating ring gas film seal.Based on the gas lubrication theory,the physical equations were built to express the gas flow state in the gap of the textured sealing rings.The established governing equations were solved numerically by the finite difference method.A numerical simulation of the hydrodynamic pressure distribution was modeled in the sealing gap of the floating ring seal.The maximum gas opening force and minimum leakage rate were selected as the optimal criteria for the structural parameters.The effect of the structural parameters of the elliptical micro-textured holes on the sealing performance under specific working conditions was analyzed,and then the optimal range of structural parameters for better sealing performance was obtained.The numerical solution of the established theoretical model of the lubricating gas flow in the sealing gap of micro-textured floating ring gas film had a little error with the comparison model,which could effectively analyze the hydrodynamic lubrication performance of the lubricating gas flow state.The hydrodynamic effect and the gas opening force could be strengthened with the increasing rotational speed and the inlet pressure of the medium gas.The leakage rate of the medium gas increased significantly with the increase of the inlet pressure,the leakage rate decreased with the improvement of the rotational speed,but the decrease was relatively small.The main affecting factors of the geometrical parameters of elliptical micro-textured holes on the gas film opening force of the floating ring gas film seal were sorted in order:area ratio>shape ratio>texture depth>rotational inclination angle.The primary affecting factors on the medium gas leakage rate of the sealing device were ranked in order:texture depth>shape ratio>area ratio>rotational inclination angle.Within the analysis range of rotational speed and inlet gas pressure,the lubricating effect and sealing performance of the floating ring gas film seal were affected by the geometrical parameters of the micro-textured holes on the surface of the shaft sleeve.The specific structural parameters of the elliptical micro-textured holes recommended to be preferentially would be used as follows:shape ratioγ=3∶1,area ratio Sp=11%,rotational inclination angleβ=0°,and micro-textured hole depth ht=1μm,to obtain excellent sealing performance.The existence of the elliptical micro-textured holes on the surface of the shaft sleeve can improve the sealing performance of the floating ring gas film seal.Selecting appropriate surface texture parameters can achieve the effect of reducing friction and improving the lubrication.The gas opening force of the eccentric floating ring gas film seal is enhanced when the leakage rate of the sealing device decreases.The results of this study can provide a theoretical reference for the processing and manufacturing of the floating ring gas film seal.