低Re对某小型涡扇发动机性能影响

低雷诺数问题是影响高空长航时无人驾驶飞机的动力装置性能的关键因素之一.定量分析了低雷诺数效应对某小型大涵道比涡扇发动机性能的影响.当雷诺数减小到一定程度后,各部件的性能将发生改变.在发动机整机环境下,增压级和低压涡轮的进口叶弦雷诺数相对更低,受飞行高度和速度的影响也更大.在发动机共同工作条件的作用下,各部件的匹配关系将发生变化,除部件效率的降低以外,部件流通能力的衰减也引起发动机性能的降低.涡轮前温度的限制将使发动机转子转速下降,低雷诺数效应加剧,从而导致发动机性能的进一步降低,推力迅速减小,但发动机涵道比的增加可以减小因部件性能衰退引起的耗油率上升的趋势.

Analysis of effects of low Reynold’s number on small turbofan engine

Problem caused by low Reynold’s number is one of main factors affect performance of high altitude endurance unmaned vehicle engines. Effects of low Reynold’s number on a small high bypass turbofan engine were discussed.The effects can make the performance of the engine’s components change when Reynold’s number decrease to some extend. Inlet blade chord Reynold’s Number of booster and low pressure turbine is lower than that of other components of the engine, and will be affected strongly with flight altitude increase and flight velocity decrease. The reduction of engine’s performance is due to component performance decline and engine re-match resulting from low Reynold’s effects on component performance. Not only efficiency of component, but also reduction of component’s mass flow, lead to the performance degradation of the engine. The rotator speed reduction (because of turbine inlet total temperature’s limit) enhances the low Reynold’s effects and hence reducing engine’s performance, engine thrust decrease rapidly, but increase of engine bypass ratio partly compensate the rise of specific fuel consumption caused by the component performance decline.