Jet cooling for rolling bearings: Flow visualization and temperature distribution

•Simulated and measured flow behaviours inside jet cooling ball bearings are given.•The higher temperature appears at the lower oil volume fraction position.•Average oil volume fraction in bearing cavity rises with a larger nozzle number.•Temperature decreases with a larger nozzle number due to better cooling effect.

To achieve an efficient cooling for the rolling bearing, a further investigation on cooling methods is necessary. The oil-jet cooling for high-speed ball bearings was investigated. The two-phase flow inside the ball bearing 7210 were analysed and verified through tests. The heat transfer was also considered. The circumferential air-oil distribution inside the bearing appears a periodic variation between two adjacent nozzles. The bearing temperature distribution is deeply affected by the air-oil distribution. The higher temperature always appears at the lower oil volume fraction position. The average oil volume fraction increases with a larger nozzle number. The nozzle number should be no more than four considering its effect on the oil volume fraction and the oil supply mechanism complexity. The nozzle number and the jet velocity have larger influences on the oil volume fraction when bearing speed is lower than 20,000 r/min. When bearing speed is larger than 40,000 r/min, the bearing speed affects the oil volume fraction much more than the multiple-nozzle oil-jet cooling mechanism parameters. The results are useful for the advanced precision cooling mechanism design of the rolling bearing.