Experimental and CFD analysis of a gas-lubricated foil thrust bearing for various foil configurations

Abstract

Thrust foil bearings operating at hydrodynamic conditions are self-acting (aerodynamic) bearings that support high-speed shafts at mild loading conditions with air as a lubricant and are generally used in low-power gas turbines. This paper presents an experimental study and a detailed computational analysis of dynamic characteristics of the foil thrust bearing (FTB) in terms of load-carrying capabilities as a function of thrust runner speed and gap between the bearing assembly and the runner by considering the effect of bearing parameters such as number of foils, shape of the foils, and assembly of foils on the bearing pad. The parametric study was conducted on a newly conceptualized bearing test rig capable of rotating up to 45,000 rpm speeds that measured the axial loads of the air foil thrust bearings (AFTB). The computational model of the foil thrust bearings for various configurations with top foils is simulated using multiphysics software for foil deflections and pressure distributions on the foil surface. The numerical results were compared with the experimental values, while the air foil thrust bearings with multilayered foils called cascaded foils (patented) had higher load capability in comparison to other conventional bearing models.

Keywords

• self-acting
• air foil thrust bearing
• cascaded foils
• square foils
• wedge film
• pressure profile
• and stiffness