Effect of Surface Roughness on Contact Pressure of Static Seals : Sealing Characteristics of Knife-Edge Seals

Abstract

In this paper, the sealing mechanism of knife-edge seals was explained and a new type of knife edge was developed. The following results were obtained: (1) The sealing mechanism of knife-edge seals was divided into three types according to the width of the flat area on the apex of the knife edge: (a) the penetration type, (b) the indentation type, and (c) the intermediate type. The Pc/l-values of the compressive force for sealing were the lowest in the case of type (a). (2) The developed knife edge had a sealing mechanism of the penetration type (a). The Pc-values of contact pressure for sealing were nearly equal to the Meyer's hardness in the sealing surface layer, regardless of both the surface roughness and the sealing surface finish. In the cases where sealing materials of copper, carbon steel and stainless steel were utilized, the Pc/l-values were approximately 15-40, 45-110 and 80-190 kN/m, respectively.