涡扇发动机外涵流道一体化精细设计

Refining of the Integral Bypass Duct Design for Turbofan Engine

外涵流道气流是发动机推力主要来源之一,外涵流道设计对整机性能有着重要的影响。外涵流道主要由中介机匣、外涵机匣、核心机外机匣、调节机构以及燃滑油管路等部件组成。其中,中介机匣分流环与核心机外机匣连接处的突扩结构以及管路等各种突兀结构,产生外涵流道的大量损失。为了解决上述问题,基于外涵流道一体化评估系统,系统分析外涵流道中突兀结构的流动损失特性。为了降低中介机匣与外涵连接结构的突扩程度,提出中介机匣分流环尾缘下偏的改进措施,精细设计2°、4°、6°3种下偏角,以及直线型、上凸型两种下偏型面,并且对比分析了各工况下的收益评估。结果表明,上凸型分流环尾缘下偏结构能够有效降低中介机匣的突扩损失,提升外涵流道的性能。

Bypass duct is main source of aircraft power,and its design has important influence on the performance of the whole machine.The bypass duct consists of compressor intermediate duct,bypass shroud,core shroud,blade adjuster and fuel and oil pipe.The sudden expansion structure in the junction between splitter and core shroud and the abrupt pipe structure leads lots of loss in bypass duct,which reduces the mixer efficiency and engine performance.In order to solve this problems,according to the loss mechanism of bypass duct,a lean splitter trailing structure was proposed.The lean splitter trailing structure could smooth the abrupt expansion junction between splitter and core shroud,and reduce the loss in CID exit.The lower loss of CID improved inlet flow quantity of bypass duct,and subsequently reduced the loss of bypass and increased the total pressure in the exit of bypass outlet.In order to reduce the degree of sudden expansion of the connecting structure between the intermediate casing and the external culvert,an improvement measure was proposed to improve the downward deviation of a line type and a curve type lean splitter trailing structure.The three downward deviation angles of 2°,4°and 6°were finely designed,as well as linear and upper abrupt pipes.With a comparative analysis of the profit evaluation under various working conditions,the results show that the upper abrupt pipe diversion ring trailing edge deflection structure can effectively reduce the sudden expansion loss of the intermediate casing and improve the outer culvert flow path performance.