Characterization And Gas Sealing Performance Analysis Of Three-Dimensional Rough Surfaces

Valve is one of the most important components used for fluid transmission,which is the indispensable fluid control equipment in such industries as petroleum,chemical,power station,long-distance pipeline,shipbuilding,nuclear,various low-temperature projects, aerospace and marine oil extraction.As application conditions become increasingly harsh,the durability and reliability of the valve get more and more attention.For example,the high-pressure static sealing valves used in aerospace engines have often to suffer a large span of temperatures,a wide range of pressure changes,as well as high vacuum and other harsh environments.So,in addition to meeting the high parameters and new requirements,how to improve sealing performance,reliability and lower the costs has become one of the problems that the valve industry has to solve.For the development of static sealing valve,except to comply with the relevant standards to make macro-structural design reasonable and ensure the process quality,looking for the relationship between the micro-geometrical topography of the rough interfaces and the leakage becomes an important method to improve its sealing performance.Starting with the characterization of 3D surface topography,this paper introduces two advanced micro/nano-surface measurement techniques- Scanning Electron Microscopy (SEM) and Atomic Force Microscope(AFM).Using the two techniques,rough surfaces manufactured by different processing methods have been measured actually.To simulate the roughness surface is the foundation to study on the relationship between surface topography and surface functional effects.Based on the autoregressive(AR) model, the technology of digital filter was used to generate the rough surfaces that have the given autocorrelation function(ACF).By controlling the character of the specified ACF,the Gaussian distribution surfaces having different texture features can be generated.This paper mainly focuses on studying the influence of the rough surface topography on the gas sealing effects.Based on the average flow model,we carry out an analysis of gas flow in the narrow gap taking rough surface topography parameters into account.The calculated results indicate that these topography parameters have a significant effect on the flow factors and load capacity of rough surface.The relationship between 3D rough surface topography and the gas sealing performance is established. The conclusions of this paper provide certain theoretical basis and implementation methods to design sealing surfaces on various sealing conditions.At the same time,it can also be a reference for precision machining of sealing surfaces.