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According to the traditional lubrication theory, the smoother the friction pairs the better the friction performance. But in recent years, a large number of theoretical and experimental results have shown that the friction surface with microstructure can effectively improve the tribological performance of friction pairs. For smooth surface and micro-dimple surface with different shapes of friction pairs, the two-dimensional finite element model is established based on the Navier–Stokes calculation equation of the fluid, and the effect of hydrodynamic effects arising from micro-dimple structure with different shapes on friction performance of friction pairs is analyzed. Through friction and wear testing, the friction properties of smooth surface and micro-dimple surface friction pairs are compared and analyzed. Theoretical simulation and experimental verification show that the surface of friction pairs with micropits can obviously improve the lubrication conditions of friction pairs and effectively improve the tribological properties of friction pairs.

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A model of spiral oil wedge hydrodynamic bearing is first established, and a numerical simulation of the fluid region is carried out by Fluent. The influence of inlet pressure and rotation speed on the cavitation area in the oil film divergence region is analyzed, and the cavitation shape, size, and location of the cavitation area are also compared and analyzed; at the same time, the influence of noncondensing gas (NCG) mass fraction on the oil film flow field is studied. The results show that the results of the numerical simulation are in agreement with the experimental results. The change of the inlet pressure and rotational speed can affect the disappearing position of the cavitation, but it has almost no influence on the appearing position of the cavitation. The increase of the inlet pressure can reduce the cavitation effectively, as well as the area of cavitation and number of large volume cavitation. But the increase of the rotational speed promotes the production of cavitation obviously and increases the number and area of cavitation and the possibility of complete cavitation. The NCG content in lubricating oil has a certain influence on the lubrication performance and bearing capacity.

Based on the finite finite difference method, the Reynolds equation, the flow equilibrium relationship of oil film gradient, and the oil film thickness equation are solved for different groove locations and depths in two-axial groove sleeve bearings. The oil film pressure, extent of the cavitation zone, and carrying capacity of two-axial groove sleeve bearings are computed at different oil groove locations and depths. With the increase of oil groove depth, the oil film pressure of two-axial groove sleeve bearings decreases noticeably, and the bearing capacity decreases gradually. It can be concluded that the maximum oil film pressure and bearing capacity of two-axial groove sleeve bearings are lower than that of the common sleeve bearing. With the groove position moving along the circumferential direction, the oil film pressure peak heights and bearing capacities decrease and then increase. The oil film pressure peak heights and load capacities reach maximum when the position of the two-axial oil groove is about 20° and 200°. It has been proven that different positions of oil grooves show different influences on the extent of the cavitation zone. The first oil groove is always located in the full oil film region, and the second oil groove may be located in the full oil film region or the cavitation region because of the change of distance from the convergent wedge of the bearing. The cavitation area firstly decreases and then increases with the movement of the groove in the circumferential direction.