Novel fluid foil compound bearings incorporating superconducting magnetic field for reusable rocket turbopumps: Lubrication characteristics and nonlinear rotor dynamics

A novel fluid foil compound bearing incorporating superconducting magnetic field was proposed for the development of maintenance-free reusable rocket turbopumps, which could combine the friction-free advantages of superconducting magnetic bearings with the high stability of foil bearings. Liquid nitrogen was chosen to simulate the cryogenic fluid environment of rocket turbopumps. Theoretical models were developed to analyze the lubrication characteristics and nonlinear rotor dynamics of fluid foil compound bearing-rotor system. Static and dynamic characteristics of the fluid foil compound bearing were calculated, including the distribution of fluid film pressure, deformation of top foil, stiffness and damping coefficients. The influence of superconducting magnetic force, nominal clearance, degree of unbalance, and foil structure loss factors on the nonlinear vibrations of the bearing-rotor system was discussed.