Thermo Hydrodynamic (THD) Computational Analysis For Tilting Pad Thrust Bearings (TPTBs)

Abstract

The report details a thermo-hydrodynamic (THD) analysis for the static and dynamic force performance of TPTBs. The goal is to deliver a modern predictive tool for TPTBs to be further integrated into the XLTRC2 software suite.The model couples a generalized Reynolds equation for the film pressure, including cross-film viscosity variation and turbulent flow effects, a 3D thermal energy transport equation for the film temperature, and a heat conduction equation for pad temperature. Numerical solution of the governing equations with approximate boundary conditions delivers pressure and temperature fields toward the calculation of a TPTB load capacity, shear drag power loss, and required flow rate. A small amplitude thrust collar motion (perturbation) analysis produces first-order pressure fields to calculate the bearing axial stiffness and damping (frequency reduced) coefficients. To check the accuracy of the model, predictions are benchmarked versus archival test data for a six-pad TPTB (228 mm OD) under specific load of 0.5 to 2.0 MPa and operating with rotor speed of 1.5 to 3.0 krpm (36 m/s). The predictions of the current THD model are in a good agreement with the test data with a maximum difference of 8% for pressure field, 17% for pad temperature, 20% for fluid film thickness, and 8% for power loss.