New mathematical model for the morton effect based on the THD analysis

Abstract

A new model for analyzing the Morton effect is presented. Previous studies of the Morton effect were either simplified or rigorously detailed requiring huge computational effort. The present work describes the new model which tries to combine accuracy of the model and computational efficiency. Perturbation method was used for the governing equations of the lubrication theory. The averaging method was applied to the equations of motion, facilitating large time steps for the numerical integration process, thus, greatly reducing the computational effort. The estimation of the spectral radius of transition operator was proposed as a convenient indicator for the rotordynamic system’s stability threshold. As a concrete example a double overhung turboexpander supported on 5-pad tilting-pad bearings was considered, which has been previously studied experimentally and analytically by Schmied and others in 2008.