Aerodynamic Analysis of Compliant Thrust Foil Bearings

Abstract

In turbo-expanders, the shaft rotates at a very high speed (i.e. 100000 RPM). At this high speeds, normal bearings cannot be used as it results in high friction and wear of the bearings. That is the reason; we are going to use gas foil bearings as a recent and advanced alternative. Here, in this project we are going to design bearings required to support the shaft which runs at a very high speed. Current project concentrate to analyse the load bearing capacity of the thrust bearings. In the analysis Reynolds’ Equation is used to know the pressure distribution of these bearings. The Reynolds’ Equation is solved by using FINITE DIFFERENCE METHOD and using many assumptions to know the pressure distribution of the thrust bearings. Finite Difference Method is a numerical technique by the principle of discretization to find the approximate solutions of engineering problems. The result comes after a many number of iterations based on a convergence condition. We are using MATLAB (Matrix Laboratory) software to implement Finite Difference Method to solve Reynolds’ Equation. A MATLAB program is written which contains multiple loops that solves the Reynolds’ Equation and gives Pressure plots. After the pressure distribution is known, load carrying capacity of the bearing is calculated and their variations with different parametes are presented. The results of this foil thrust bearings are compared with the load carrying capacity of rigid bearings. The analysis was also done for different types for foil bearings by taking different materials of the bump foil.