Three Dimensional Dynamic Model of TEHD Tilting Pad Journal Bearing—Part I: Theoretical Modeling

Abstract

This paper is focused on a new modeling method of threedimensional (3D) thermoelastohydrodynamic (TEHD) cylindrical pivot tiltingpad journal bearing (TPJB). Varying viscosity Reynolds equation and 3D energy equation are coupled via lubricant temperature and viscosity relationship. Threedimensional finite element method (FEM) is adopted for the analysis of: (1) heat conduction in shaft and bearing pad, (2) thermal deformation of shaft and pad, (3) flexible bearing pad dynamic behavior, and (4) heat conduction, convection, and viscous shearing in thin lubricant film. For the computational efficiency, modal coordinate transformation is utilized in the flexible pad dynamic model, and pad dynamic behavior is represented only by means of modal coordinate. Fluid film thickness is calculated by a newly developed node based method, where pad arbitrary thermal and elastic deformation and journal thermal expansion are taken into account simultaneously. The main goal of this research is to provide more accurate numerical TPJB model than developed before so that the designers of rotating machinery are able to understand the bearing dynamic behavior and avoid unpredicted problem by selection of physical parameters.