The Effect of Finite Width in Externally Pressurized Foil Bearings With Porous Shaft. (1st Report, In the Case of Negligible Small Surface Roughness).

Abstract

In this paper, the effect of finite width on the hybrid performance of externally pressurized foil bearings with a porous shaft is examined theoretically based on the finite width bearing theory. In the analysis of governing equations in order to save computation time and to improve the convergency of solution, the two dimensional Reynolds equation is reduced to the ordinary differential equation by expanding the film pressure to the Fourier series with respect to the axial coordinate. The reduced Reynolds equation and force balance equation for the foil are solved iteratively by the finite element technique, and the numerical solutions for pressure and gap height are obtained for a wide range of bearing width-to-diameter ratio under the various combinations of supply pressure, permeability of porous shaft and wrap angle of foil. It is found from the results that the bearing width has significant effect on the pressure and gap height of the bearings.