Research On The Performance Of Bump Foil Journal Bearings

Bump foil journal bearing is a new kind of gas foil bearings. They have been successfully used in various types of rotating machinery, such as turbochargers and gas turbine engines. This type of bearing offers several advantages over a conventional rigid surface bearing or ball bearing, including higher load capacity, lower power loss, and better stability. These advantageous characteristics of bump foil bearings have been demonstrated through many experimental investigations. The foil structure of a gas foil bearing consists of two parts: a smooth top foil that provides the bearing surface and a corrugated bump foil that provides resilient support for top foil. In this type of bearing, dry-friction effects arising between the bumps and top foil and the bumps and the bearing inner surface provide the energy dissipation or damping characteristic.Because there are the top foil and bump foil in the structure of bearing, so it is difficult to set up the model of bump foil bearings compared to rigid surface bearings. When the static performance of bump foil journal bearings is analyzed, the fluid film pressure must be coupled with the deformation of the foil structure. In order to simplify the structure model, the spring element and the beam element generally are used. However, its three-dimensional shape is not considerated in this model. Firstly, the finite element method is applied to construct the elastic shell element model for foil bearings in this paper. Because the membrane stress is coupled with the plane bending stress in this model, so the model reflects defections of the bump foil and the top foil more factually. Secondly, both finite difference method and Newton-Raphson method are used to solve coupled Reynolds equation and air film thickness equation. Moreover, air film thickness, pressure distribution and load carry capacity are researched. By comparing with the test data, the method of this paper is feasible and precise. Finally that bearing speed and foil thickness have effect on the foil bearing characteristics is also discussed.Rotary shaping machinery with the elastic medium and dies are designed and made. In addition, the process of manufacturing the bearing and the experimental test system is also designed and discussed.