异形排气管的热态气动试验

Experiments of Hot Cases on Unconventional Nozzle

在发动机活动试车台上，对全尺寸的从环形过渡到腰果形的发动机排气管，进行了热态的出口压力和温度分布测试，实验结果表明：排气管出口截面的上部存在有严重的低压区，出现气流倒流的现象，产生的原因是由于发动机排气管的上壁面的扩张角过大造成的。排气管出口截面温度由上向下不断提高，上部因受冷气倒流的影响，温度只有９０℃左右，而对应排气管环形部分直接排出的燃气，由于未受冷空气的掺混，使出口截面下半的气流最高温度达４２０℃左右。

Temperature and pressure fields are measured for the exit plane of a nozzle which has the shape from doughnut to kidney on a movable engine test bench. Results indicate the upper part on exit plane of the nozzle exists an area of low pressure which induces inverse flow. The reason is that the upper wall of this nozzle has a large expansion angle. This leads to lower temperature at position near the upper part. The upper flow is affected by the cool inverse flow so that the temperature is only about 90℃.The main exhaust which directly flows out has the temperature of about 420℃ because it is unaffected by the cool inverse flow.