Abstract: Water injection pre-cooling technology is one of the feasible approaches to eliminate the thrust gap of TBCC (Turbine Based Combined Cycle) engine. A sequence of simulations were conducted numerically based on a TBCC inlet with practical flow field to research the evaporation characteristics of water droplets and pre-cooling effects of water injection on incoming air under different working conditions. The results indicate that the cooled temperature of incoming air increases gradually with the improvement of water to air ratio (W/A). The maximum cooled temperature appears to be 152.4K. In contrast, the evaporation ratio of injected water witnesses a downward trend as water to air ratio increases, while the vaporized mass of water droplets increases as usual. The water injection shows more significant pre-cooling effects at higher flight Mach number under the condition of a constant water to air ratio. The maximum evaporation ratio appears to be 83.05% with W/A=0.03 at Ma3.5. Water injection pre-cooling expands the flight Mach number of turbine mode to the maximum value of Ma2.84, namely, water injection pre-cooling widens the range of transition speed from turbine mode to scramjet mode for TBCC.

Key words: TBCC engine;Inlet pre-cooling;Water injection pre-cooling;Air to water ratio;Evaporation characteristic

摘要： 对涡轮基组合循环(Turbine Based Combined Cycle, TBCC)发动机涡轮进气道进行喷水冷却是解决TBCC发动机推力不连续问题的有效方式之一。本文基于实际流场条件选取某型TBCC发动机涡轮进气道结构，对进气道内喷水冷却特性进行了数值仿真，研究飞行器不同工况下水滴的蒸发特性及喷水对来流高温空气的预冷效果。结果表明，来流空气温度降幅随水气比提高而增大，最高温降可达152.4K。水气比提高后水滴蒸发率逐渐降低，但蒸发总量仍会继续上升。相同水气比条件下，飞行马赫数越高，喷水冷却效果越明显。在Ma3.5飞行速度和水气比0.03条件下有最高蒸发率，达83.05%。喷水冷却有效扩展了涡轮模态飞行马赫数，最高能使飞行速度提升至Ma2.84，即喷水冷却扩展了TBCC从涡轮模态向超燃冲压模态转换的衔接速域。

关键词: TBCC发动机;进气道预冷却;喷水预冷却;水气比;蒸发特性