Fractal modeling of fluidic leakage through metal sealing surfaces

Abstract

This paper investigates the fluidic leak rate through metal sealing surfaces by developing fractal models for the contact process and leakage process. An improved model is established to describe the seal-contact interface of two metal rough surface. The contact model divides the deformed regions by classifying the asperities of different characteristic lengths into the elastic, elastic-plastic and plastic regimes. Using the improved contact model, the leakage channel under the contact surface is mathematically modeled based on the fractal theory. The leakage model obtains the leak rate using the fluid transport theory in porous media, considering that the pores-forming percolation channels can be treated as a combination of filled tortuous capillaries. The effects of fractal structure, surface material and gasket size on the contact process and leakage process are analyzed through numerical simulations for sealed ring gaskets.

An Experimental Study of the Leakage Mechanism in Static Seals

“…In addition, four test pieces with different surface characteristics were designed and processed, whose leak rates were measured separately. Compared with the calculation results obtained from the fractal surface leak rate prediction model [18], the correctness and the application range of the model were verified, and the effects of different surface topographies and material properties of the four test pieces on the leak rate were analyzed as well. The proposed system was also used to perform single-factor comparison experiments, which were then combined with the theoretical prediction model to analyze the effects of the sealing surface contact load, fluid pressure, and surface apparent size on the leak rate, so that theoretical support and experimental evidence for selecting the parameters of sealing device was provided.…”

“…According to the fractal theory, the fractal surface is simplified to asperities distributed above the reference plane and pores distributed below the reference plane. The fundamental wavelengths of asperities and pores in the reference plane are l and l v , respectively, which is called the characteristic length of the asperity and the pore [18]. [18], the cross-sectional profile of the asperity and pore are given by:…”

“…The fundamental wavelengths of asperities and pores in the reference plane are l and l v , respectively, which is called the characteristic length of the asperity and the pore [18]. [18], the cross-sectional profile of the asperity and pore are given by:…”

“…However, it described the initial surface profile of rough surfaces through the asperity contact area A, resulting in the initial profile varying with the contact area A, and consequently concluded that "full plastic deformation happens to asperities before elasto-plastic deformation and elastic deformation", which is contrary to real-world observations. In our previous work [18] (the article "Fractal Modeling of Fluidic Leakage through Metal Sealing Surfaces"), we improved the M-B model (by setting up a reference surface on the fractal surface), as the original M-B model was violating real-world observations when applied to calculating the contact load; moreover, using the improved contact model, the leakage channel under the contact surface is mathematically modeled based on the fractal theory and proposed the fractal surface leak rate prediction model.…”

A new solution of the semi-metallic gasket increasing tightness level

“…In order to explain what is an in uence of the gasket's e ective width on leakage level, the mechanism of the gas ow via porous ring layer was taken to analysis. The radial ow through the porous layer in the form of ring can be described in accordance with modi ed Darcy's expression presented among others in [16,17]:…”