为探究射流预冷涡扇发动机热力性能，采用部件法建立了发动机的数学模型，开展了设计点处加力燃烧室燃料转化率对预冷效果的影响研究，分析了沿特定飞行轨迹不同来流工况下发动机喷水后的性能变化规律。结果表明，采用进气道喷水冷却能够有效提升发动机性能；在Ma2.8设计点工况，燃料转化率增加使燃烧更充分，喷水量为4%，燃料转化率从0.8增加至0.96，比冲由20057s增加至22998s，耗油率由0.179kg/(h·N)降低至0.156kg/(h·N)。沿飞行轨迹Ma2-Ma3.2过程中，射流预冷在Ma2.4-Ma2.8范围内对推力等整体性能的改善最佳；为避免来流空气进入风扇压缩时液滴的干扰，随着Ma的增加，水气比的最大值逐渐增大。当Ma大于2.8时，在水气比1%-6%范围内，比冲快速上升，在水气比超过6%后，比冲上升程度减缓。对于Ma3.2工况，水气比低于2%时，比冲因加力燃烧室燃烧效率的提升而有一定的提升；水气比达4%以后，过量水会影响加力燃烧室燃料的雾化蒸发和掺混，导致燃烧效率降低，比冲下降。

To investigate the thermal performance of jet pre-cooling turbofan engines, a m-athematical model of the engine was established using the component method. The influences from fuel conversion rate on the pre-cooling effect at the design point of the afterburner were studied, and the performance changes of the engine after spraying water under different inflow conditions along a specific flight trajectory were analyzed. The results indicate that using inlet spray cooling effectively improve engine performance; At the Ma2.8 design point operating condition, the increase in fuel conversion rate leads to more complete combustion with the water injection rate of 4%. The fuel conversion rate increases from 0.8 to 0.96, the specific impulse increases from 20057s to 22998s, and the fuel consumption rate decreases from 0.179kg/(h·N) to 0.156kg/(h·N). The jet pre-cooling provides the optimal improvement in thrust and overall performance indices in the Ma2.4-Ma2.8 range along the flight trajectory from Ma2 to Ma3.2. To avoid liquid droplets flowing into the fan compression, the suitable water to air ratio should be increased gradually with the increasing of Ma. With Ma over 2.8, the specific impulse increases rapidly at the range of 1%-6% water gas ratio, and increases flatly with the water gas ratio over 6%. For the Ma3.2 operating condition, With the water gas ratio below 2%, there is a substantial increase in specific impulse due to the improvement of combustion efficiency in the afterburner; After the water gas ratio over 4%, excessive water will affect the atomization, evaporation, mixing of fuel in the afterburner, and resulting in a decrease in combustion efficiency and specific impulse.