Heat Transfer Analysis Of Main Bearing And Oil Collecting Structure Of Aeroengine

The main shaft support bearing of the aero-engine is continuously operated under high temperature and high speed conditions.The lubrication method,under-ring lubrication can effectively reduce the working temperature of the inner ring of the bearing.The oil collecting structure in the lubrication under the ring is located inter the counter-rotating shaft.Therefore,research on the flow and heat transfer inter the counter-rotating shaft have great value in the thermal analysis of the bearing,the oil movement in the oil collecting structure and the design of the air-cooling route.In this paper,the modified velocity distribution model for flow in the counter-rotating annulus inter shaft without axial flow was established based on Karman three-layer structure of the turbulent boundary layer and numerical simulation.The formula and correlation equation for the Nusselt number of outer shaft surface was derived using the velocity distribution model following the analogy theory of momentum transfer and heat transfer.Then,the oil-air flow state in oil collecting structure was based on the numerical simulation results of the two-phase flow.The theoretical model of the counter-rotating annulus inter shaft with the oil film based on the assumption of the flow and heat transfer of the oil-air in the counter-rotating annulus inter shaft was established.Finally,a numerical calculation model for the flow and heat transfer of the bearing inner ring-shaft-oil collecting structure was established.The temperature field in the solid region and the radial thermal deformation of the bearing inner ring and high pressure shaft were analyzed.The conclusions are as follows.In contrast to the velocity distribution and the heat transfer Nusselt number of outer shaft surface,obtained by numerical simulation,the results using the modified Karman three-layer structure model for flow in the counter-rotating annulus inter shaft are in good agreement with numerical simulation.Based on the velocity distribution of the oil film and the air flow in the counter-rotating annulus inter shaft,the expression of the velocity distribution of the oil and air in the counter-rotating annulus inter shaft and the calculation method of the heat transfer coefficient of the inner wall surface of the outer shaft are given.Finally,the heat transfer analysis of the main bearing-oil collecting structure is carried out.When the bearing is working normally,the thermal deformation caused by the temperature field will not cause the change of the matching property between the inner ring of the bearing and the high-pressure shaft.