THREE-DIMENSIONAL NUMERICAL ANALYSIS OF FLOW AND HEAT TRANSFER CHARACTERISTICS OF OIL/GAS TWO-PHASE MIXTURE IN AERO-ENGINE BEARING CHAMBERS OF DIFFERENT STRUCTURES

Abstract

The change of the outlet number of bearing chambers can change the pressure distribution in the chamber and the action of the air shear force, which has an important influence on oil/gas two-phase flow and heat transfer. In this paper, the flow and heat transfer characteristics in the ventless bearing chamber and the vented bearing chamber were compared and analyzed by numerical simulation. The accuracy of the numerical model was verified by comparison with the experimental data. Three different rotor speeds were selected, and the lubricating oil distribution, the velocity of oil/gas two-phase flow, and the temperature distribution in the bearing chamber were investigated under different numbers of outlets of the bearing chamber. The heat flux and Nusselt number distribution of convective heat transfer between oil/gas two-phase flow and the outer wall at different rotor speeds were analyzed. The results show that the thickness of oil film increases in the ventless bearing chamber with increase of rotor speed, and when air flow is large, it hinders the uniformity of lubricating oil distribution and the increase of the velocity of oil/gas two-phase flow, but it can improve the uniformity of heat transfer. In the vented bearing chamber, the thickness of oil film decreases with increase of rotor speed, and the speed of oil/gas two-phase flow increases greatly, and the entraining effect of air is obvious. The research results can provide a theoretical reference for improving the number and structure of bearing chambers to improve the performance of lubricating oil system.