粗糙表面的气体密封性能研究

Gas Sealing Performance Study of Rough Surface

高精度的气体密封是现代工业和国防工业的关键技术之一,以粗糙表面干接触气体静密封问题为研究对象,基于自回归(Autoregressive,AR)时间序列的数字滤波技术,利用计算机生成具有给定自相关函数和纹理取向的高斯分布的数值化粗糙表面,根据气体在微纳米粗糙表面间隙流动理论,建立粗糙表面静接触间隙气体密封模型,通过对气体在接触间隙流动的数值模拟,分析表面粗糙度纹理方向、方均根等粗糙表面表征参数在名义气体膜厚变化时对气体泄漏量和密封压力的影响,给出粗糙表面形貌参数和密封压力与气体密封性能之间的关系。在粗糙间隙雷诺方程中引入两个气体压力流动流量因子,使得随机雷诺方程变为普通雷诺方程,从而方便工程应用。以某低温气体密封阀为例,分析泄漏量与密封载荷、表面粗糙度参数等参数之间的关系,从而为阀门密封设计提供理论基础。

High-precision gas sealing is one of the most important technologies in modern industry and defense industry.The gas sealing in a dry contact pair of rough surfaces is taken as a study object.Based on the autoregressive（AR） time series model,the technology of digital filter is used to generate the Gaussian rough surfaces that have the given autocorrelation function（ACF） and orientation parameter.According to the theory of gas flow in a micro/nano-rough-gap,the gas sealing model of rough surfaces in dry contact is set up.Through the numerical simulation of gas flow in a contact gap of rough surfaces,the influences of characterization parameters of rough surface,such as surface roughness texture direction and root mean square,on the gas leakage and sealing pressure when the nominal gas film thickness changes,are analyzed,and the relationship between rough surface topography parameter,sealing pressure and gas sealing performance is given.The random Reynolds equation for gas flow in a rough gap is reduced to a general Reynolds equation by introducing two gas pressure-driven flow factors,so that it is convenient for engineering application.Finally a low-temperature sealing valve is taken as an example,we analyze the relationship between the leakage and the sealing load and surface roughness parameters.A basic design theory for the valve sealing design is set up.