Study on Flow Field Characteristics of High-Speed Double-Row Ball Bearings with Under-Race Lubrication
Abstract
1. Introduction
2. Model and Method
2.1. Geometric Model
2.2. Meshing of Fluid Domain
2.3. Two-Phase Flow Model
2.4. Turbulence Model
2.5. Numerical Method
2.6. Validation of Simulation Methods
3. Results and Discussion
3.1. Dynamic Characteristics of Oil–Air Two-Phase Inside the Bearing
3.2. The Effect of Parameters on Oil Distribution
3.2.1. Bearing Rotational Speeds
3.2.2. Oil Supply Rate
3.2.3. Self-Rotation of Balls
3.2.4. Number of Under-Race Holes
3.2.5. Diameter of Under-Race Holes
3.2.6. Axial Position of Under-Race Holes
3.2.7. Circumferential Position of Under-Race Hole
3.2.8. Oil Viscosity
3.2.9. Oil Density
4. Conclusions
- (1)
- The oil distribution inside the bearing is dominated by centrifugal force, exhibiting asymmetric characteristics with oil enrichment at the outer ring and depletion at the inner ring (the average volume fraction on the outer ring surface is significantly higher than that on the inner ring). Circumferential oil distribution exhibits periodic variations synchronized with the number of under-race holes. Additionally, oil concentration is higher near the under-race holes and lower in regions farther away from them.
- (2)
- Increasing inner ring rotational speed reduces the oil volume fraction on both raceway surfaces, while higher oil supply rates increase it. Among these, oil supply rate is the key parameter directly determining the total oil supply quantity, while rotational speed affects the distribution pattern by indirectly regulating the migration direction of the oil. An increase in oil viscosity can elevate the overall oil volume fraction within the bearing cavity (suppressing oil flow dispersion), making it a critical physical property parameter for adjusting lubrication performance. In contrast, although an increase in oil density leads to a decrease in the oil volume fraction, the effect is insignificant, thus it can be considered an auxiliary parameter.
- (3)
- The self-rotation of balls reduces the overall oil volume fraction within the bearing cavity, causing a substantial decrease in the outer raceway’s oil volume fraction while markedly increasing that of the inner raceway. The self-rotation effect is particularly prominent at low rotational speeds, whereas it becomes negligible at high rotational speeds. This indicates that the self-rotation of balls is a critical factor requiring special attention under low-speed operating conditions, and its coupling effect with rotational speed directly determines the lubrication performance.
- (4)
- Compared with single-sided oil supply structures, double-sided oil supply structures exhibit higher circumferential oil volume fractions. Changes in the circumferential position of under-race holes do not alter the overall oil distribution within the bearing cavity. Increasing the number of under-race holes simultaneously enhances the oil volume fractions on both the inner and outer ring surfaces. However, the influence of oil supply hole diameter on the volume fraction follows a “first-increase-then-decrease” trend, with an optimal diameter existing. Therefore, synergistic optimization of the oil supply structure and parameters (number and diameter) is required in under-race lubrication design to improve lubrication uniformity.
Author Contributions
Funding
Conflicts of Interest
References
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Geometry Parameters | Specification |
---|---|
Inner ring diameter (mm) | 50 |
Bearing width (mm) | 40 |
Pitch diameter (mm) | 68.5 |
Contact angle (°) | 30 |
Ball diameter (mm) | 12.3 |
Ball number | 20 |
Mesh Element Numbers | Difference in Flow Between Inlet and Outlet |
---|---|
1,816,758 | 5.83% |
3,209,238 | 2.46% |
4,028,005 | 2.38% |
Name | Type |
---|---|
Inner raceway | Moving wall, no-slip |
Outer raceway | Stationary wall, no-slip |
Ball | Moving wall, no-slip |
Cage | Moving wall, no-slip |
Inlet | Mass-flow inlet |
Rotational Speeds (rpm) | Literature Oil Volume Fraction | Simulation Oil Volume Fraction | Relative Error |
---|---|---|---|
5000 | 0.01335 | 0.01323 | 0.90% |
8000 | 0.00954 | 0.00963 | 0.94% |
11,000 | 0.00748 | 0.00736 | 1.60% |
14,000 | 0.00563 | 0.00557 | 1.07% |
17,000 | 0.00439 | 0.00447 | 1.82% |
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Hu, X.; Lin, J. Study on Flow Field Characteristics of High-Speed Double-Row Ball Bearings with Under-Race Lubrication. Aerospace 2025, 12, 861. https://doi.org/10.3390/aerospace12100861
Hu X, Lin J. Study on Flow Field Characteristics of High-Speed Double-Row Ball Bearings with Under-Race Lubrication. Aerospace. 2025; 12(10):861. https://doi.org/10.3390/aerospace12100861
Chicago/Turabian StyleHu, Xiaozhou, and Jian Lin. 2025. "Study on Flow Field Characteristics of High-Speed Double-Row Ball Bearings with Under-Race Lubrication" Aerospace 12, no. 10: 861. https://doi.org/10.3390/aerospace12100861
APA StyleHu, X., & Lin, J. (2025). Study on Flow Field Characteristics of High-Speed Double-Row Ball Bearings with Under-Race Lubrication. Aerospace, 12(10), 861. https://doi.org/10.3390/aerospace12100861