附加涵道风扇系统叶尖涡轮流动特征

针对一种可极大提升涵道比的气驱附加涵道风扇推进动力系统开展研究，采用数值模拟手段重点分析了其核心部件叶尖涡轮的流动特征和工作机理，为后续发展这种大涵道比推进动力奠定理论基础。研究表明:叶尖涡轮实质上是具有低稠度低展弦比特征的轴流涡轮，稠度可低至0.6，展弦比可低至0.4。低展弦比造成的叶尖涡轮间隙泄漏损失增大为原来的2倍，泄漏涡径向侵入叶根，主流流动损失加剧，大大降低了低稠度涡轮能量提取效果；稠度降低会使得喉道位置迁移，导致气流偏转和膨胀加速能力大幅下降；基于这一结构，提出有效提能区和能量提取率来阐明其做功机理并表征低稠度叶尖涡轮的出功能力。 

Flow characteristic of tip turbine of additional ducted-fan system

Based on a novel high bypass ratio turbofan propulsion system with additional tip-driving fan, the flow characteristics and working mechanism of the core components tip-turbine were investigated using numerical simulation, which laid a theoretical foundation for the further development of high bypass ratio propulsion. Research results indicated that tip-turbine was essentially the axial flow turbine with low solidity and low aspect ratio characteristic, solidity can be as low as 0.6, aspect ratio as low as 0.4. The reduction of solidity caused the migration of throat position, which led to a substantial decrease in the flow deflection and the acceleration of the expansion; the gap leakage loss caused by the low aspect ratio was 2 times larger than the original one, and the influence of leakage vortex was gradually extended to the vicinity of the root of the blade, which reduced the effective extraction of energy area and the energy extraction rate greatly; for the novel power system, effective extraction of energy region and energy extraction rate were proposed to measure the specific work of tip-turbine qualitatively and quantitatively.