Static Characteristics of Liquid Annular Seals with Square-Hole Pattern

Abstract

The theoretical and experimental study is carried out to investigate the static characteristics of the liquid annular seals with a square-hole pattern in seal stator. The momentum equations with turbulent coefficients and the continuity equation, which are averaged across the film thickness, are numerically solved to obtain the pressure distributions in the seal clearance and the leakage flow rate. Semi-empirical pressure jump coefficients are used for evaluation of both pressure jumps due to the expansion at the passage of the fluid from the land to the square-hole region and the contraction from the square-hole to the land region. The numerical results of the pressure distribution and the leakage flow rate agree well with the experimental results, which proves the validity of the numerical analysis. The pressures decrease in the axial direction and their distribution has periodical unevenness due to the square-hole pattern in the seal stator. The square-hole pattern seal as well as the parallel-grooved annular seal yields a lower leakage flow rate than conventional seals with smooth surfaces. This reduction of the leakage flow rate is attributed to the pressure jump phenomena with energy loss induced by the axial flow passage across each step between the land and the square-hole region.