Optimization Research On Oil Collector Of Aero-engine Intermediary Bearings

The oil collector is an important part of the aero-engine intermediate bearing lubrication system.The oil collecting efficiency of the collector affects the lubrication and cooling of the bearing directly.In order to improve the oil collecting efficiency,prolong the bearing life and increase reliability,the oil-air two-phase flow in the prototype oil collector of an aero-engine intermediate bearing is numerically simulated by the method of computational fluid dynamics.Improving structures for the oil collector are proposed,and the relation between collecting efficiency and structure parameters are researched.The flow in the prototype oil collector is studied at various settings of inner ring rotating speed and oil flow rate by the CLSVOF(Coupled Level Set and Volume Of Fluid)model,a numerical method of multi-phase flow.The flow field and oil movement in the prototype oil collector are analyzed,and the reason of oil loss is revealed.The results show that the oil is split into two branches of oil flow from the entry port and collided with the inner surface of the cage,one branch to the inside of the bearing,and the other to the leak port.The oil which flows to the leak port acumulates near the inside of the oil dam.The main reason for low oil collecting efficiency is that the lubricating oil accumulated near the inner side of the oil dam is absense of force that drives the oil to the inner direction of the bearing.When the oil accumulated at the oil dam reaches a certain amount,the oil overflows the oil dam and leaks into the bearing cavity.On the basis of fully understanding the regular pattern of oil flow in the prototype oil collector,three improveing structural schemes are proposed: cone inner surface cage,inclined entry port and raised height of oil dam.The flow field of the improved oil collectors were numerically simulated.The results show that the improved scheme of the cone inner surface cage has the best effect,an efficiency of 99.7%,which is much higher than the prototype oil collecting efficiency,is achieved at the cone angle of 16°.Raised height of oil dam can block the flow of oil to the leaking port and increase the oil collecting efficiency by a small amount.The effect of the inclined entry port is between the aforementioned two shemes.