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Floating ring bearing has the advantages of simple structure and high operating speed and is widely used in turbocharger and aero-engine. However, many harsh working conditions cause the floating ring bearing to produce starved lubrication and failures. Here, we investigated the starved lubrication characteristics of floating ring bearing via theoretical modeling and numerical simulation. We first established a theoretical model of starved-boundary lubrication based on the Reynolds equation for floating ring bearing. And meanwhile, an oil-film ratio coefficient is introduced into the theoretical model to reflect the degree of starved lubrication. We then analyzed the influence of inlet-boundary conditions (flow rate, oil-film thickness) on the starved-lubrication performance of floating ring bearings. The results showed that the flow rate obviously affects the bearing area of inside and outside oil film, and the oil-film ratio coefficient inside the bearing. When the oil supply is lower than 10 mL/min, the floating ring bearing is in a serious starved-lubrication state, and the oil-film area of bearing is reduced by 30%. The favorable oil supply flow rate can obviously improve the lubrication conditions, and also can predict the starved state of inner oil-film. Our study provides a theoretical basis for the fault detection of floating ring bearing. • Studied the mechanism of oil-starved lubrication on floating ring bearing. • Established model of oil-starved lubrication to calculate lubrication characteristics for floating ring bearing. • Calculated lubrication characteristics under different lubrication conditions. • Analyzed the influence of oil supply on bearing lubrication characteristics. [ABSTRACT FROM AUTHOR]

Stern shaft deformation caused by ship maneuvering will lead to stern bearing lubrication failure and wear. Based on the displacement superposition method, the deflection equation of the stern shaft under the action of the interface force and the propeller load was established. The fluid-solid coupling model of the stern bearing was established by using the averaged Reynolds equation, the Greenwood-Tripp model, and the influence coefficient method. The model was experimentally validated. The influence of the shaft bending deformation caused by the propeller load change on the lubrication characteristics is discussed. The results show that the shaft bending deformation leads to the changes in lubrication characteristics along the axial and circumferential directions. Compared with the vertical load alone, the existence of horizontal propeller load will significantly reduce the minimum nominal oil film thickness and friction coefficient. Under hydrodynamic lubrication, the direction of horizontal load has little effect on friction coefficient. • The displacement superposition method is used to calculate the bending deformation of the propeller shaft. • A fluid-solid coupling model of marine stern bearing is established. • The friction coefficient of the oil-lubricated bearing were tested to verify the model. • The lubrication performance of stern bearing during the ship severe turning maneuver is discussed. [ABSTRACT FROM AUTHOR]

Extensive wear appears in the case of dry contacts, or when the lubrication of the contacting surfaces is not appropriate. The aim of this research is to improve the mixed elastohydrodynamic lubrication in hypoid gears by the optimization of manufacture parameters for tooth surface processing. A full numerical analysis of the thermal mixed EHL in hypoid gears is applied. The equation system and the numerical procedure are unified for a full coverage of all the lubrication regions including the full film, mixed, and boundary lubrication. In the hydrodynamically lubricated areas the calculation method employed is based on the simultaneous solution of the Reynolds, elasticity, energy, and Laplace's equations. In the asperity contact areas the Reynolds equation is reduced to an expression equivalent to the mathematical description of dry contact problem. The real geometry and kinematics of the gear pair based on the manufacturing procedure is applied, thus the exact geometrical separation of the mating tooth surfaces is included in the oil film shape, and the real velocities of these surfaces are used in the Reynolds and energy equations. The transient nature of gear tooth mesh is included. The oil viscosity variation with respect to pressure and temperature and the density variation with respect to pressure are included. The non-Newtonian behaviour of the lubricant is considered. Using this model, the pressures, film thickness, temperatures, and power losses in the mixed lubrication regime are predicted. By using the developed method, the influence of the manufacturing parameters on the conditions of mixed elastohydrodynamic lubrication is investigated. On the basis of the obtained results recommendations are formulated to improve the mixed EHL and the efficiency of face-milled hypoid gears. • A full numerical analysis of the mixed EHL in hypoid gears is performed. • The influence of the manufacture parameters on mixed EHL in hypoid gears is investigated. • Recommendations are formulated to improve the EHL characteristics of hypoid gears by optimizing the manufacture procedure. [ABSTRACT FROM AUTHOR]