Research on the Static Performance of Multi-Cantilever Foil Bearing with the Fully Coupled Elastic Hydrodynamic Solution

Abstract

As an indispensable part of modern supporting technology, advanced hydrodynamic bearing still plays an irreplaceable role in turbomachinery. High speed with slight load foil bearing has been the inevitable choice for the turbo machine to improve the performance in the 21st century. In spite of the successful application of this oil-free supporting technology in engineering, as summarized by Radil and Dellacorte, for lack of the in-depth research needed to fully understand the basic operating fundamentals uniquely inherent in compliant foil bearings as well as the data required to validate computer models, the absence of reliable performance-prediction methods and design guidelines has become one of the most critical technical hurdles which impede the application and widespread use of aerodynamic bearings. This paper presents a new type of foil bearing which consists of the top foil with multi cantilever spring as supporting foil named multi-cantilever foil bearing (MCFB). A fully coupling solution method consisting of the deformation equation of the foil as well as the pressure in the bearing has been present using the cylindrical shell theory with nonlinear large deformation. Moreover, the coupling law between the elastic deformation and the steady state properties has been clarified. Finally, the coupled elastohydrodynamic governing equation of steady state is obtained. A three pad MCFB with cantilever array of7 column in circular direction and 13 row in the width direction has been analysed by solving the coupled Reynolds equation with non-uniform meshed FEM. The initial position of the bottom foil with cantilever foil array in the bearing house is determined. Regarded to these graphs, these results indicate that the system static performance prefers good under different conditions. The method proposed in this paper perfect solves the problem of the coupling between the top foil deformation and its Reynolds equation which greatly facilitates the solution of the elastohydrodynamic coupling solution. The speed and precision of the coupling solution are improved remarkably.