romac

University of Virginia

Rotating Machinery and Controls Laboratory

P.O. Box 400746

122 Engineer’s Way

Charlottesville, VA 22904

(434)924-3292

(434)982-2246(fax)

Rotating Machinery and Controls Laboratory

MAXBRG 3.8

 

Consultant: Minhui He

Faculty: Paul Allaire

Project Start Date: September 1996

Report Number: 458

 

Project Overview:

Widely used in turbomachinery, the fluid film journal bearing is critical to a machine’s overall reliability level. The objective of this project is to develop a state of the art thermoelastohydrodynamic (TEHD) algorithm for industrial journal bearing analysis. The first version of the resulting computer code MAXBRG was completed and released in May 2003.

 

Many advanced models are employed in this finite element based algorithm. The pressure is calculated from the generalized Reynolds equation. The pad and film temperatures are obtained from a unique two-dimensional energy equation. Turbulence is automatically handled throughout the flow computations. Deformations of various components, such as pad and journal, can also be included. A coupled film-pad approach is utilized to achieve outstanding numerical stability.

 

This algorithm can be used to analyze directly lubricated bearings as well as conventional fixed geometry and tilting pad bearings. Modeling of pressure dam bearings is extended to include adiabatic thermal effects. In addition to the flooded lubrication condition, it can be applied to several special conditions including starvation, high ambient pressure and axial flow. Moreover, the computer code is flexible, allowing the users to select and combine a variety of modeling options according to their specific needs and engineering judgment.

 

 

MAXBRG will continue to be maintained and upgraded in the future. One coming upgrade is to add fluid inertia effect to the pressure calculation. The inertia effect can be significant for water-lubricated bearings due to water’s low viscosity. Other planned upgrades include addition of shear stress in the determination of pad tilt angles, addition of a correlation factor to improve the pad deformation predictions, and addition of a taper at pad trailing edge.