Evaluation of Floating Ring Seals for Centrifugal Compressors Using the Finite Element Method

Abstract

The use of liquid ring type oil seals in centrifugal compressors was essential for high pressure applications dating back to the early 1960’s. The analysis of high pressure oil seals was first documented in the literature in the mid-1970’s following a series of compressor instability problems that made it clear that a better understanding of how seals influence the overall rotor stability was necessary. To produce compressor designs at higher speeds requires that an adequate method of predicting the oil seal influence on rotor dynamic stability be available for the designer. With the enhanced capability of personal computers and improved finite element models of the oil film thermal and hydrodynamic solutions, it is now possible to more accurately predict the dynamic characteristics of the oil seals. This paper presents a series of predicted results from a currently available advanced state of the art computer analysis for high pressure oil seals. The evaluation of several high pressure compressor seal designs illustrates the current capability for analytical predictions for various seal bore geometries. Conclusions and recommendations for the design of liquid ring seals are presented, which can give the compressor designer guidance for application to future high performance compressor liquid seal designs.