Loss of lubrication (LOL) is a severe problem in transmission systems, whereby the temperature increases continuously until failure. The temperature and flow-field distributions are complicated during this process. Limited research exists on the temperature and flow-field distributions and on heat generation of the transmission system during LOL. This study uses the computational fluid dynamics method to establish an oil–gas, two-phase flow model for the asymmetric bearings, and calculate the oil volume fraction on the bearing surface. In addition, a dynamic heat generation calculation method was proposed based on the kinematic viscosity change of the oil–air mixture during the LOL process. The temperature distribution of the large and small rollers and raceway surface during the LOL process was analyzed using a simulation method. The injection parameters were optimized to avoid gluing of the large roller. The internal temperature distribution has a strong positive correlation with the lubricant distribution during the LOL process. Moreover, the lubrication and temperature distributions on the large roller side are worse. A temperature reduction of approximately 25% is possible upon the increase of the number of oil inlets.
In this study, two-row tapered roller bearings (TBR) with different rib structures were tested under the condition of loss of lubrication. It was found that the double-row TBR with outer ring rib structure worked normally after 40 min of the test, but the inner ring The bearing of the side structure has failed. In order to explain this phenomenon, computational fluid dynamics (CFD) numerical simulation models of two structural bearings were established, and the flow characteristics of the oil in the bearing cavity under the conditions of full lubrication and loss of lubrication were studied by the method of discrete inlet oil volume. The research results show that, in the fully lubricated state, the oil volume fraction of the double-row TBR outer ring wall of the outer ring rib structure is 11.296 times higher than that of the inner ring rib structure. Moreover, the volume fraction of oil on the roller surface is 2.07 times higher in the outer ring rib structure than the inner ring rib structure. The volume fraction of lubricating oil in the bearing cavity decreases as the speed increases; however, the double-row TBR with the outer ring rib structure still shows a better lubrication effect than the inner ring rib structure. In the final stage of the loss of lubrication, the volume fraction of the bearing flow field of the outer ring rib structure is twice that of the inner ring rib structure, making the outer ring rib structure double-row tapered roller bearing (TBR) more dry Operational ability.
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