TURBULENT-FLOW, FLEXURE-PIVOT HYBRID BEARINGS FOR CRYOGENIC APPLICATIONS

The thermal analysis of flexure-pivot tilting-pad hybrid (combination hydrostatic-hydrodynamic) bearings for cryogenic turbopumps is present ed The advantages of this type of bearing for high speed operation are discussed. Turbulent bulk-flow, variable properties, momentum and ene rgy transport equations of motion govern the flow in the bearing pads. Zeroth-order equations for the flow field at a journal equilibrium po sition render the bearing flow rate, load capacity drag torque, and te mperature rise. First-order equations for perturbed flow fields due to small amplitude journal motions provide rotordynamic force coefficien ts. A method to determine the tilting-pad moment coefficients from the force displacement coefficients is outlined. Numerical predictions co rrelate tr ell with experimental measurements for tilting-pad hydrodyn amic bearings. The design of a liquid oxygen, flexure-pad hybrid beari ng shows a reduced whirl frequency ratio and without loss in load capa city or reduction in direct stiffness and damping coefficients.