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

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 fluidstructure 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 beta. 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-xx, K-xy, K-yx, K-yy, C-xx, C-xy, C-yx and C-yy of the gas film, leading to higher equivalent stiffness of the gas film K-eq.