고압 다단 펌프 시일의 누설 및 동특성에 관한 연구

Bump foils in air foil bearings are investigated using theoretic analysis, FEM (Finite element method), and experimental method. To analyze the dynamics of bump foils, the governing equation is used by bending moment equation and theory of the thin curvature beam in analytic method. All forces, reactions, and friction forces between bump foils and the housing or the top foil are considered from the geometric form of bump foil applying normal forces on the central top of bump. Plane strain-stress method considered by three components in the xy plane, and the triangle elements are used for FEM analysis. To measure stiffness and damping coefficients of bump foil, the test setup is made with exciter, accelerometer, and gap sensors. An increase in the friction coefficient between the top foil and the bump is a more effective method of achieving both Coulomb damping and higher stiffness. This paper presents the comparison between FEM analytic and experimental results.