可变面积涵道引射器对变循环发动机性能影响

分析了变循环发动机前、后涵道引射器的几何调节方式，建立了变循环发动机稳态及过渡态数学模型，并考虑了前涵道引射器和模态选择阀门由于面积突变引起的局部总压损失，模拟了变循环发动机单外涵模式、双外涵模式及模态转换过渡态过程中，前、后涵道引射器面积对发动机性能和稳定性的影响，并与NASA试验数据进行了对比.结果表明：单外涵模式，放大前涵道引射器内涵进口面积会减小变循环发动机的回流裕度，但可增大风扇和核心驱动风扇级的喘振裕度；在由单外涵模式过渡至双外涵模式的模态转换后期，减小后涵道引射器外涵进口面积可减缓风扇压比的下降；建议前涵道引射器选择总面积保持不变而内涵进口面积改变，后涵道引射器选择内涵进口面积保持不变而外涵进口面积改变的调节方式.

Impact of variable area bypass injector on variable cycle engine performance

The geometry regulating laws of forward and rear bypass injectors of variable cycle engine were analyzed. A mathematic model capable of calculating the variable cycle engine steady and transition performance was established. It considered the local total pressure loss caused by sudden area change at forward bypass injector and mode selector valve. The impacts of geometry regulating laws of forward and rear bypass injectors on variable cycle engine performance and stability were simulated with single bypass mode, double bypass mode and mode transitioning, and the simulation results were compared with NASA test data. The results indicate the opening of forward bypass injector''s inner bypass area can decrease recirculation margin and increase fan and core drive fan stage surge margin in single bypass mode. During the late period of transforming from single into double bypass mode, the reduction of fan pressure ratio will diminish by closing rear bypass injector''s outer bypass area. It''s suggested that the forward bypass injector''s inner bypass area should be changed, and the total area should be kept unchanged, while the rear bypass injector''s outer bypass area should be changed, and the inner bypass area should be kept unchanged.