Analyzing the two-phase flow behavior in bearing lubrication is crucial for understanding friction and wear mechanisms, optimizing lubrication design, and improving bearing operational efficiency and reliability. However, the complexity of oil–air two-phase flow in high-speed bearings poses significant research challenges. Currently, there is a lack of comparative studies employing different simulation strategies to address this issue, leaving a gap in evidence-based guidance for selecting appropriate simulation approaches in practical applications. This study begins with a comparative analysis between experimental and simulation results to validate the reliability of the adopted simulation approach. Subsequently, a comparative evaluation of different simulation methods is conducted to provide a scientific basis for relevant decision-making. Evaluated from three dimensions—adaptability to rotational speed conditions, research focuses (oil distribution and power loss), and computational economy—the findings reveal that FVM excels at medium-to-high speeds, accurately predicting continuous oil film distribution and power loss, while MPS, leveraging its meshless Lagrangian characteristics, demonstrates superior capability in describing physical phenomena under extreme conditions, albeit with higher computational costs. Economically, FVM, supported by mature software ecosystems and parallel computing optimization, is more suitable for industrial design applications, whereas MPS, being more reliant on high-performance hardware, is better suited for academic research and customized scenarios. The study further proposes that future research could adopt an FVM-MPS coupled approach to balance efficiency and precision, offering a new paradigm for multi-scale lubrication analysis in bearings.

Tapered roller bearings are extensively utilized in the aerospace industry owing to their superior load-carrying capacity and extended service life. However, the majority of research conducted by scholars on the subject of bearing lubrication has focused on ball and cylindrical roller bearings. There is a paucity of research on the internal lubricants and air distribution of tapered roller bearings under oil jet lubrication conditions. This paper presents a computational fluid dynamics (CFD) simulation model specifically designed for the oil jet lubrication of tapered roller bearings. The flow field inside the bearing cavity is analyzed under various operating conditions, and the impact of different parameters on lubrication performance is quantitatively assessed using the oil return efficiency as a metric. Additionally, an experimental test stand for the jet lubrication of tapered roller bearings was developed. The simulated oil return efficiency was compared with experimental data, revealing discrepancies within 10%, thereby validating the accuracy of the CFD model. The findings suggest that directing the oil jet toward the smaller end of the bearing, appropriately increasing the nozzle flow rate, and utilizing positive jetting can significantly improve the lubrication performance of tapered roller bearings.

Under-race lubrication is an effective oil supply method for high-speed angular contact ball bearings, but the relationship between internal oil–air two-phase flow distribution and end oil return behavior remains insufficiently understood. In this study, a Volume of Fluid (VOF)-based oil–air two-phase flow model was developed for an under-race lubricated angular contact ball bearing and validated experimentally. The effects of oil flow rate, rotational speed, inlet-hole axial position, diameter, and number were investigated. The maximum relative error between the numerical and experimental oil return ratios was 3.17%. At 3000 rpm, increasing the oil flow rate from 65 to 140 L/h increased the average oil volume fraction on the rolling element surfaces from approximately 0.037 to 0.089. In contrast, increasing rotational speed reduced oil retention on bearing component surfaces and the oil return ratio at the large-clearance end. At 140 L/h, the oil return ratio decreased from approximately 97% at 3000 rpm to 86.5% at 6000 rpm. Shifting the inlet holes toward the small-clearance end enhanced cage wetting but reduced oil retention on the rolling elements and large-clearance-end oil return. Within the investigated range, a mid-plane inlet position, smaller inlet-hole diameter, and larger number of inlet holes were more favorable for oil delivery to the rolling elements while maintaining a relatively high oil return ratio.

The oil collection performance of a planetary oil scoop is important for the lubrication of planetary bearings. This study investigates the effects of operating and structural parameters on oil collection performance and performs multi-objective optimization. A three-dimensional oil–air two-phase flow model was established using the VOF method. The effects of oil inlet flow rate, rotational speed, oil dam height, oil feed hole diameter, oil injection distance, and number of oil feed holes were investigated. An experimental test rig was developed to validate the numerical model. A Kriging surrogate model, Sobol sensitivity analysis, and NSGA-II were then used for multi-objective optimization. The results show that increasing rotational speed, oil dam height, and oil feed hole diameter improve oil collection efficiency, while increasing oil inlet flow rate reduces it. A critical change occurs at an oil injection distance of approximately 25 mm. The maximum deviation between experimental and numerical results is 13.84%. Sensitivity analysis identifies oil feed hole diameter as the main influencing factor. The optimization results show a trade-off between oil collection efficiency and collected oil flow rate, providing a reference for planetary oil scoop design.