Rotordynamics of Impeller Eye Seals with Wear-Damaged Teeth in Centrifugal Compressors

Abstract

This paper investigates the influence of labyrinth seal teeth wear damage on the performance and the rotordynamic characteristics of impeller eye seals in centrifugal compressors. A well-established CFD-perturbation model was employed to predict the seal rotordynamic coefficients. The inclusion of at least an approximate shroud leakage path chamber is preferred for an accurate prediction of seal-inlet swirl velocity and flow-induced rotordynamic forces. It was found that impeller eye seals with teeth damage: (a) suffer significant leakage increases due to the increased seal clearance and (b) produce higher seal-inlet swirl velocity and thus larger rotordynamic forces that tend to cause the system to become unstable. It was also found that variations of the distorted teeth tip geometries have an insignificant influence on both leakage and rotordynamic coefficients for a given seal radial clearance. The impeller shroud leakage path influence on seal-inlet swirl velocity W0 and the effect of W0 were also explored to better understand the rotordynamic characteristics of the eye seal subject to various degrees of teeth damage.