The influences of bump foil structure parameters on the static and dynamic characteristics of bump-type gas foil bearings

Abstract

Bump-type gas foil bearing is a special type of sliding bearing, especially suitable for supporting rotors with light loads and high speeds. In this paper, a deformation model of bump foil is established by using elastic mechanics theory. A fluid-structure interaction algorithm is proposed according to Reynolds equation of compressible gas. On this basis, a method for calculating the static and dynamic characteristics of the bump-type gas foil bearing is established considering the structure parameters of the bump foil. The presented model is validated using the data reported in the existing research. The gas film pressure distribution, gas film thickness distribution of the bearing, and the influences of bump foil structure parameters on the static and dynamic characteristics of the bearing are studied with an example. Results show that, decreasing the bump foil thickness t_B or increasing the bump pitch s will increase the limiting load-carrying capacity W and decrease the attitude angle β. And increasing t_B or decreasing s will decrease the friction torque T_r and increase the side leakage flow of gas Q_z, resulting in less friction heat generation and faster heat dissipation. Increasing t_B or decreasing s will increase the absolute values of $K_{\mathit{xx}}$ , $K_{\mathit{xy}}$ , $K_{\mathit{yx}}$ , $K_{\mathit{yy}}$ , $C_{\mathit{xx}}$ , $C_{\mathit{xy}}$ , $C_{\mathit{yx}}$ and $C_{\mathit{yy}}$ of the gas film, leading to higher equivalent stiffness of the gas film $K_{\mathit{eq}}$ .