变循环发动机模式转换对加减速性能的影响

Effects of variable cycle engine mode transition on performance of accelerating and decelerating

变循环发动机具有单外涵与双外涵两种工作模式,根据使用场景或发动机性能匹配需求可能在加减速过程中进行模式转换。为了评估模式转换对加减速性能的影响,建立了可在加减速过程中进行模式转换性能模拟的过渡态性能计算模型,对比分析了引入模式转换后的加减速特性。结果表明:模式转换控制规律对风扇工作线和发动机加速性有影响,设计时应使风扇工作线变化平稳,同时在保证发动机稳定工作的前提下缩短模式转换时间;模式转换可使减速过程中的风扇最小喘振裕度从2%提高至15%,从而消除风扇喘振裕度对减速供油规律的限制,进而改善发动机减速性能。

The variable cycle engine can operate in two modes:single and double bypass.Depending on us⁃age scenarios or engine performance matching requirements,mode transition may occur during acceleration and deceleration process.To assess the effects of mode transition on acceleration and deceleration performance,a transition state performance calculation model was developed in this study.This model can simulate mode transi⁃tion during acceleration and deceleration.The acceleration and deceleration characteristics after introducing mode transition were compared and analyzed.The results show that the mode transition control law will affect the fan operating line and engine acceleration performance,it should be designed to make the fan operating line change smoothly,and shortening the mode transition time while ensuring stable engine operation.Mode transition can increase the minimum stability margin of the fan during deceleration from 2%to 15%,thereby eliminating the limitation of fan stability margin on deceleration fuel supply law and improving engine deceleration perfor⁃mance.