A Mixed Zero-Equation and One-Equation Turbulence Model in Fluid-Film Thrust Bearings

Abstract

A thrust bearing is a rotary bearing that facilitates rotational movement between components and is specifically engineered to provide support for a load that is parallel to the axis of rotation. The generation of the inter-surface film pressure is attributed to the relative motion (rotation) of the surfaces, which results in the lubricant being drawn into the converging wedge formed between them. The interface between the unmovable and moving parts is demarcated by a slender layer of lubricating fluid, including but not limited to oil, water, air, or other process fluid. The conventional zero-equation model can be enhanced to achieve higher precision in forecasting and reduce dependence on empirical data, owing to its inherent limitations. A novel turbulence model that combines zero-equation and one-equation approaches has been developed and implemented in the recently introduced modeling tool package for thrust bearings. In the Prandtl one-equation turbulence model, the length scale is a necessary but undetermined term. A novel mixed model has been implemented utilizing the Prandtl one-equation along with a novel-length scale. The tool package is a Thermo-Hydrodynamic (THD) code that involves iterative computations between the Reynolds’ equation, turbulence equation, energy equation within the film, and conduction equation in pad and runner. The new model yields an eddy viscosity that exhibits a substantial level of proximity to both eddy viscosity transport (EVT) and direct numerical simulation (DNS), and exhibits significant enhancements in comparison to the traditional Ng–Pan zero-equation turbulence model.