Improvement of Operating Characteristics of High-Speed Hydrodynamic Journal Bearings by Optimum Design: Part I— Formulation of Methodology and Its Application to Elliptical Bearing Design

Abstract

This paper describes the optimum design methodology for improving operating characteristics of hydrodynamic journal bearings and its application to elliptical journal bearing design used in high-speed rotating machinery. The hybrid optimization technique combining the direct search method and the successive quadratic programming is applied effectively to find the optimum solutions. In the optimum design of elliptical journal bearings, the design variables such as vertical and horizontal radial clearances, bearing length-to-diameter ratio and bearing orientation angle are determined to minimize the objective function defined by the weighted sum of maximum averaged oil film temperature rise, leakage flow rate, and the inversion of whirl onset speed of the journal under many constraints. The results obtained are shown in graphical form for a wide range of journal rotational speed. Comparing the optimized operating characteristics with the characteristics calculated from the random selected design variables, the effectiveness of optimum design is clarified.