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Purpose: This paper aims to analyze the temperature field and the heat transfer performance of the counter rotating dual rotor bearings (CRDRB) based on the air phase flow field at different speeds to provide effective support for the lubrication and the thermal design of CRDRB. Design/methodology/approach: In this study, taking H7006C angular contact ball bearing as an example, based on the flow visualization technique and the thermal analysis methods, the effects of outer ring speed on the air phase flow field, the temperature field and the heat transfer in bearing cavity were investigated. Findings: Results indicated that there were more complex turbulent air vortices in CRDRB cavity. Turbulent cyclones in critical contact zone reduced the heat dissipation capacity of air. Compared with single rotor bearing with a static outer ring, the average heat transfer coefficient reduced by 11.78% and the average temperature raised by 3.06 K inside CRDRB cavity. Under the influence of outer ring rotation, the high temperature area in ball-inner raceway contact zone and pocket raised and reduced by 160.13% and 30.48%, respectively. The outer ring rotation had opposite effect on the heat dissipation of raceway contact zone and pocket. Originality/value: The air phase flow field characteristics and the heat transfer performance of CRDRB were revealed and analyzed from the mechanism. An area quantification method was presented as an auxiliary mean of the thermal analysis to evaluate the heat transfer performance of bearing. [ABSTRACT FROM AUTHOR]

The six-DOF-balls, five-DOF-inner ring and three-DOF-cage were all considered to promote the quasi-dynamic model of ball bearing. The motions and heat generation obtained via the model were then input to a precise numerical model for cage thermal analysis. The oil–air flow pattern inside bearing cavity, the influence of cage parameters such as the pockets shape, methods of guiding, clearance, on bearing cage heat dissipation performance were all investigated. The results indicate that, at ultra high rotation speed, suitable cage parameters are significant to air–oil flow and thermal dissipation inside bearing cavity. [ABSTRACT FROM AUTHOR]

In high speed rotation, the strong airflow inside ball bearing cavity has become a key factor which seriously affects bearing lubrication performance. By adding groove structures to the non-contact area of bearing inner ring surface, a guiding method for lubrication enhancement was proposed. Via simulating an oil droplet flowing on the grooved surface, the guiding mechanism for groove structure was analyzed, and the capillary force played an important role during the guiding process. The influence of groove structure parameter and bearing motions on guiding performance were all discussed, the groove structure was designed and experimentally verified. Compared with the general bearing, grooved bearing has a lower temperature rise, which indicates the effect of groove structure on bearing lubrication enhancement. • A novel method for bearing lubrication enhancement by groove structure was proposed. • The guiding mechanism of groove structure in oil droplet flow was investigated. • The groove structure was designed and the effect was experimentally verified. [ABSTRACT FROM AUTHOR]

• Bearing thermal characteristic with different oil-air supply methods was compared. • Field synergy principle was used to explain bearing internal flow and lubrication. • It was found that lateral oil-air flow is better for bearing at certain speeds. High precision models were established to investigate airflow pattern and lubrication performance inside bearing cavity with different oil-air supply methods. The coupling technique of Level-Set function and VOF method was used to track the oil-air interface, and the migration and diffusion process of oil droplets inside bearing cavity were obtained. A high-speed oil-air lubrication test rig was designed and set up, bearing temperature rise with outer ring and lateral oil-air lubrication methods at different rotation speeds were tested and compared. Finally, combined with the internal flow and temperature field distribution, the synergistic analysis was applied and the lubricant flow and heat dissipation performance of bearing internal cavity and key areas were all estimated. [ABSTRACT FROM AUTHOR]