Numerical Analysis of Leakage Characteristics of Valve Sealing Structure

Taking the sealing structure of safety valve in nuclear reactor system as the research object, a three-dimensional rough surface model of sealing structure based on porous medium theory is established in this paper. The calculation formula of leakage rate of sealing structure is deduced by Darcy's law. The effects of roughness, autocorrelation length and sealing specific pressure on surface characteristics, as well as the effects of roughness and sealing surface contact width on leakage rate were studied. The results show that the relationship between the roughness and the sealing performance is not linear, and it is limited to only use the roughness as the evaluation index of the sealing performance. When the roughness is certain, the different autocorrelation length will also affect the porosity and permeability of the sealing interface, thus affecting the sealing performance of the safety valve. The decrease of sealing specific pressure leads to the increase of contact height, which makes the porosity between valve seat and disc increase rapidly, resulting in the enhancement of leakage characteristics of sealing structure. The increase of roughness makes the leakage rate increase nonlinearly, and the increase of sealing surface contact width makes the leakage rate decrease linearly.