Abstract: 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.

Key words: Digital filter, Roughness, Sealing, Texture feature, The average flow model