Analysis of a hydrodynamic seal with helical grooves

Abstract

High speed turbogenerators are generally gas cooled and hydrodynamic seals are often used to prevent cooling gas leakage. The seal needs to run essentially at a low eccentricity in order to maintain an uninterrupted oil film all around the shaft. The flow of the oil towards the gas side should be minimized to avoid the contamination of oil with gas. The hydrodynamic seal studied consists of two lands, one on the gas side with helical grooves and the other exposed to ambient air with a wedge. The two lands are separated by a circumferential oil supply groove. The leakage of oil towards the gas side was investigated for different helical groove parameters such as the number of grooves, the helix angle and the groove depth. The effects of these parameters on the performance of the hydrodynamic seal in terms of load support, induced moment, attitude angle, temperature rise and friction force are reported. Equations governing the fluid flow were solved by the finite element method.