A TRANSIENT BASED, NUMERICAL ANALYSIS OF FLOW AND PRESSURE FIELDS INSIDE A VARIABLE DEPTH RAYLEIGH STEP HYDRODYNAMIC POROUSTHRUST BEARING

摘要

This paper presents the numerical solution for the development of flow patterns and pressure profiles for two types of Variable Depth Rayleigh Step thrust bearings (VDRS) using two different methods for feeding the working fluid (inlet boundary conditions):, (a) an inlet central jet and (b) a smooth porous section located at the bottom of the Rayleigh step. This type self-acting hydrodynamic bearing is essentially hybrid in nature, resulting from the combination of two classical geometries, the slider and the Rayleigh step. The parameters used in this study include: (i) geometric (fractional portion relating to the total circular geometry, the depth and angle of the recess, and the bottom plate porosity and permeability) and (ii) operational (top smooth plate angular velocity(ies), inlet jet volumetric flow rate and porous plate fluid supply pressure.rnThe offered solution is isothermal and is obtained using the commercially available ANSYS (CFX) software package. The package uses the full Navier-Stokes equations modified to accept the Darcy and Forchheimer terms. The resulting velocity and streamline maps, pressure patterns as well as stiffness and damping are presented on a parametric basis.