An Efficient Scheme for Estimating Rotordynamic Coefficients of Liquid Annular Seals by a Pseudo Spectral Method

Abstract

A prevalent challenge in rotordynamic analysis is the accurate estimation of the dynamic coefficients of seals. Experimental techniques are seldom adopted due to the demanding procedure involved, leading to computational fluid dynamics (CFD) being the predominant approach, although inherently time-intensive. A novel methodology utilising the pseudo spectral method (PSM) is employed to derive the dynamic coefficients of seals from the turbulence modified, extended form of the Reynolds lubrication equation. A modified form of the commonly used Hirs' turbulence lubrication theory is employed which takes into account both Poiseuille and Couette flows, the combination of flows typically experienced in seals. Appropriate boundary conditions are implemented for the solution, incorporating empirical coefficients to represent inlet pressure loss, exit pressure recovery, and the Lomakin effect. The suggested methodology demonstrates a good corroboration with experimental results and CFD, particularly at smaller eccentricity ratios. The proposed framework is appealing for creating an analysis environment in which a limited equation set may be readily modified to design journal bearings and seals efficiently and within acceptable accuracy levels, all the while with rapid computation speed.