Thermohydrodynamic analysis of product-lubricated hydrostatic bearings in turbulent regime

Abstract

A bulk-flow thermohydrodynamic (THD) analysis is developed for accurate predictions of the static and dynamic performance characteristics of turbulent flow product-lubricated hydrostatic journal bearings (HJBs). Pointwise evaluation of temperature and hence liquid properties is achieved through the solution of the energy equation in the fluid film with an adiabatic boundary assumption justified for HJBs with large mass flow rates. Fluid inertia on film lands and at recess edges are preserved in the analysis. Flow turbulence is accounted through turbulence shear parameters based on friction factors derived from Moody's formulae. The effects of fluid compressibility and temperature variation in the recess are included. A finite difference scheme is implemented to solve the governing equations on the film lands, while the Newton-Raphson scheme is used to update the recess pressures and to satisfy the mass continuity requirement at each recess. Comparisons between numerical results and experimental data of turbulent flow water HJBs and liquid hydrogen (LH2) HJBs show very good correlation and demonstrate the correctness and accuracy of the analysis and the numerical scheme. Large temperature-rises are determined in a roughened stator liquid oxygen (LO2) HJB, which affect strongly the operating clearance and hence the bearing performance. Thermal effects are important in cryogenic liquid HJBs.