Tilting pad thrust bearings are a key component of marine propulsion shaft systems. The dynamic performance of thrust bearings has a significant influence on the propeller vibration. To investigate the axial oil film stiffness of tilting pad thrust bearings, a two-dimensional thermohydrodynamic model incorporating the vibration frequency is developed. The test apparatus and experimental identification model are also constructed. The axial oil film stiffness is experimentally identified at different speeds, loads, and temperature employing the hammer impulse excitation. The axial oil film stiffness between theoretical and experimental results is compared. The discrepancies are not more than 7% for 30 kN operation cases but increase with axial static load. This is partially because the influence of the pivot stiffness becomes obvious with the axial static load increase and cannot be ignored. The results indicate that axial oil film stiffness is at a magnitude of 10⁹ N·m⁻¹. Compared to foundation stiffness of the thrust bearing system, the influence of axial oil film stiffness needs to be considered for bearing–rotor system design of marine propulsion systems in engineering practice.

To improve the performance of a heavy-loaded and high-speed hydrodynamic bearing, partial texture is designed on the journal surface. A three-dimensional thermo-hydrodynamic analysis model is developed based on the computational fluid dynamics method. Thermal conduction of bearing bush and journal, heat convection on the air-bearing surface, viscosity–temperature effect, and cavitation effect are taken into account. Performance of textured and un-textured high-speed journal bearing under different eccentricity ratios and different external loads is compared. The results indicated that partial texture on journal surface can play a positive role for large eccentricity ratio conditions in this study, and the textured bearing has a higher load carrying capacity, a lower maximum oil pressure, and a lower oil temperature rise than the un-textured bearing based on an optimal design of texture.

In order to improve the inadequacy of the current research on oil droplet size distribution in aero-engine bearing chamber, the influence of oil droplet size distribution with the oil droplets coalescence and breakup is analyzed by using the computational fluid dynamics-population balance model (CFD-PBM). The Euler–Euler equation and population balance equation are solved in Fluent software. The distribution of the gas phase velocity field and the volume fraction of different oil droplet diameter at different time are obtained in the bearing chamber. Then, the influence of different initial oil droplet diameter, air, and oil mass flow on oil droplet size distribution is discussed. The result of numerical analysis is compared with the experiment in the literature to verify the feasibility and validity. The main results provide the following conclusions. At the initial stage, the coalescence of oil droplets plays a dominant role. Then, the breakup of larger diameter oil droplet appears. Finally, the oil droplet size distribution tends to be stable. The coalescence and breakup of oil droplet increases with the initial diameter of oil droplet and the air mass flow increasing, and the oil droplet size distribution changes significantly. With the oil mass flow increasing, the coalescence and breakup of oil droplet has little change and the variation of oil droplet size distribution is not obvious.

The calculation with the determiend load is more useful for engineering applications as the external load is easier to obtained than the bearing eccentricity. However, the calculation method based on the the determined load for journal bearing with complex structure is still difficult to meet requirement. This paper presents a calculation method to seek proper bearing eccentricity with a determined external load according to response surface methodology. The relationship between the relative eccentricity and attitude angle of the journal bearing and the external load is determined according to response surface optimization. The Navier-Stokes and elastic deformation equations are adopted during calculating lubricating properties. The validity of the calculation method are verified with the experimental results. Moreover, the method is also proved to be applicable to the calculation of the fixed load based on Reynolds equation.

The dynamic performance of a new high-speed spindle supported by water-lubricated hybrid bearings is experimentally studied on a test rig. The present design allows the speed of the spindle up to 30,000 rpm, with a bearing internal diameter of 40 mm, which makes it possible to simulate many actual machining processes. Some experiments have been presented to study the mechanical and thermal behaviors of the spindle and its supporting hybrid bearings. The maximum temperature rise is less than 15°C with a speed of 30,000 rpm and a water supply pressure of 2.5 MPa. The spindle radial run-out of the rotational frequency is about 1 µm. Stability of the spindle system has been improved. The experimental results indicate that water-lubricated hybrid bearings are valuable choices to replace ceramic bearings and air bearings as support for spindles under high-speed, high-precision, and heavy-load machining conditions.

The research of oil/air two-phase flow and heat transfer is the fundamental work of the design of lubrication and heat transfer in aero-engine bearing chamber. The determination of impact state criterion of the moving oil droplets with the wall and the analysis of oil droplet deposition characteristics are important components. In this paper, the numerical analysis model of the impact between the moving oil droplet and the wall is established by using the finite volume method, and the simulation of oil droplet impingement on the wall is carried out. Then the effects of oil droplet diameter, impact velocity, and incident angle on the characteristic parameters of impact state are discussed. The characteristic parameters include the maximum spreading length, the maximum spreading width, and the number of splashing oil droplets. Lastly the calculation results are verified through comparing with the experimental results in the literature. The results show as follows: (1) The maximum spreading width of oil droplet firstly increases and then slows down with the incident angle and the oil droplet diameter increasing; (2) when the oil droplet diameter becomes small, the influence of the incident angle on the maximum spreading length of oil droplet is obvious and vice versa; (3) with the impact velocity and diameter of oil droplet increasing, the maximum spreading width of oil droplet increases firstly and then slows down, and the maximum spreading length increased gradually; (4) the number of splashing oil droplets increases with the incident angle and impact velocity increasing; and (5) compared with the experimental data in literature, the critical dimensionless splashing coefficient $Kc$ proposed in this paper can better distinguish the impact state of oil droplet.