Abstract: The oil leakage of bearing cavity directly affects the safety of aero-engine, but the existing research lacks the exploration of oil sealing performance of bearing cavity under air-bleeding oil-sealing conditions. An experimental device for oil-air two-phase leakage flow characteristics in sealing clearance of bearing cavity is designed and built, a numerical solution model for oil-air two-phase leakage flow characteristics in bearing cavity is established, on the basis of mutual verification of numerical values and experimental results, the oil-air two-phase distribution and critical sealing characteristics of bearing cavity sealing clearance are studied. The results show that:When the air-bleeding pressure is higher than the critical sealing pressure, the lubricating oil and the pressurized air mix in the oil cavity to form a complex oil-air two-phase state, the higher the oil level, the larger the oil-air mixing area; When the air bleed pressure is lower than the critical sealing pressure, the lubricating oil flows into the sealing clearance, the state of oil-air interface is wavy or strip, and the oil flows into the air cavity first in a fluid-like flow, and then in a membrane-like flow. The sealing clearance width increases from 0.05 mm to 0.20 mm, and the critical sealing pressure increases by 221.5 %. When the oil level increases from 30 mm to 120 mm, the critical seal pressure increases by 129.2 %. The oil level affects the oil leakage flow by affecting the oil acceleration, and the sealing gap width affects the oil leakage flow by affecting the oil acceleration and throttling effect. The research content provides theoretical basis for the analysis of leakage flow characteristics and oil-sealing pressure determination of critical seal pressure.

Key words: bearing cavity, air-bleeding oil-sealing, oil-air two-phase, leakage flow, critical oil-sealing pressure