Session: 23-02 Gas Foil Bearings

Paper Number: 151491

Development of Nonlinear Bump Stiffness Model and its Effect on Structural Stiffness and Nonlinear Rotordynamic Characteristic 

Bump foils are the most widely used in foil bearings, but the behaviors of bump foils are complicated and their characteristics have been a focus of research for decades. Bump foils are usually modeled as stiffness and damping are accounted for through friction with other parts. These nonlinear characteristics of the bump foil of radial foil bearings can be observed during both manufacturing and operational processes because of their inherent structural properties such as bump geometry, forming process, and complicated contact behavior with bearing housing.  These nonlinear characteristics are one of the challenges in analyzing the characteristics of the foil bearings. In this study, the nonlinear stiffness of bump foils in flat configuration has been experimentally measured and compared with various analytical models. Furthermore, the same bump geometry but with a curved configuration for actual radial foil bearings was used to measure the structural non-linear stiffness in the bearing level in a push-pull setup and compared with analytical prediction. Finally, the nonlinear bump stiffness model was adapted to the radial foil bearing to calculate overall bearing stiffness and damping coefficients, and stability characteristics through modal analysis and transient time domain orbit simulations. Lastly, the non-linear stiffness model of the bump foils will be verified by measuring bearing coefficients using shaker systems.

Presenting Author: Woongeon Lee University of Texas at Arlington

Presenting Author Biography: Woongeon Lee is a Ph.D. candidate student of mechanical engineering at the University of Texas at Arlington(UTA). His research field is oil-free turbomachinery with non-contact foil bearings. He is a research assistant at the Turbomachinery and Energy Systems Laboratory(TESLAB) at UTA. He prototypes and tests foil bearings at Bellkim Energy LLC. His current research topic is a nonlinear structural model for the analysis of air foil bearings.

Authors:

Woongeon Lee University of Texas at Arlington
Ehiremen Ebewele The University of Texas at Arlington
Daejong Kim The University of Texas at Arlington