On the Lubrication and Stability Behaviors of a Conical Hybrid Floating Ring Bearing with Thermal Effects

The conical bearing can withstand both journal and axial load because of the conical-shape fluid film, and an investigation concerning the thermodynamic lubrication and stability properties is proposed for a conical hydrostatic/hydrodynamic floating ring bearing theoretically and experimentally. The finite element method is coupled with the finite difference method to solve the variable-viscosity Reynolds equations, thermal energy equations, and the corresponding boundary conditions for the inner and outer films in a floating ring equilibrium state, and the conical bearing-rotor dynamic and stability performance models are built up with the perturbation theory and Routh-Hurwitz method. The primary characteristics parameters that are obtained under different operational conditions suggested that there presents a significant temperature gradient distribution over the lubricated domain, the thermal effects decrease the load carrying capacity, friction power loss, and stiffness and damping coefficients, and the viscous dissipation influences the variation of threshold instability speed with eccentricity and reduces its maximum value. In experiments, the temperature distributions of the oil leakage flow are measured to compare with the calculated results for the validation of the mathematic model using an infrared thermal imager, and the thermal effects need to be taken into consideration for the bearing lubrication analysis and design.