关键词: 预冷吸气式组合发动机, 预冷器, 换热微细管束, 振动分析, 可靠性评价

Abstract: For the problem of heat exchange micro-tube vibration reliability of diaphragm micro-channel pre-coolers which was one of the key components of pre-cooled air breathing combined cycle engines, the method and mathmatical model for calculating the natural vibration characteristics of heat exchange micro-tubes were developed, and the vibration modes and their mechanism of heat exchange micro-tube with the action of high speed air flow were studied. Then, the vibration modes including the vortex shedding excitation vibration, the turbulent buffeting vibration and the elastic excitation vibration were taken into account, and the reliability evalutating model of pre-coolers with heat exchange micro-tube vibration failure mode was derived. The pre-cooler heat exchange micro-tube vibration reliability of change rules were revealed. The results show that the natural vibration frequency of heat exchange micro-tube is affected by the parameters including outside diameter, pipe wall thickness, adjacent support plate spacing, material properties and so on, and the vibration modes of heat exchange micro-tube have the characteristics of sine function. Three important vibration modes including the vortex shedding excitation vibration, the turbulent buffeting vibration and the elastic excitation vibration those may happen in the heat exchange micro tubes of pre-cooler with the action of high speed air flow. And with the increasing of flow velocity of cooled working fluid, the heat exchange micro-tube vibration reliability of pre-coolers decreases firstly, and then increases and approaches a certain value. In order to avoid the resonance of heat exchange micro tubes, the structural parameters may be designed rationally with the operating profile and the flow and heat transfer characteristics may be also taken into account.

Key words: pre-cooled air breathing combined cycle engine, pre-cooler, heat exchange micro-tube, vibration analysis, reliability evaluation