基于膨胀度可控的 SERN 设计及试验验证简

 单边膨胀喷管（SERN）是超燃冲压发动机的关键部件，由于其几何非对称，在发动机点火/熄火瞬间，SERN会产生较大的冷热态俯仰力矩差，影响飞行器的稳定性。现有解决方法主要是利用几何/气动调节方式，但都有不利影响。本文提出了基于膨胀度可控的SERN设计的新方法，将采用该方法得到的喷管模型B与基准喷管模型A进行了对比研究，并对模型B进行缩比冷流试验，试验与数值模拟结果吻合良好。研究结果表明：飞行马赫数为4.5时，模型B的推力系数比模型A仅仅下降了0.1%，而模型B比模型A的冷热态俯仰力矩差减小了80.49%；飞行马赫数为6.5时，模型B的推力系数比模型A不仅上升1.1%，同时模型B比模型A冷热态俯仰力矩差还下降12.73%，验证了设计思想的正确性，为提高SERN俯仰力矩性能提供了一种新的思路。

Design and Experimental Validation of SERN Based on Controllable Expansion Degree Distribution

The single expansion ramp nozzle (SERN) is a key component of a scramjet engine. However, because of its asymmetrical geometry large pitch moment differences exist from the SERN at the start and shut-down moment of the scramjet engine, which seriously affects the stability of the aircraft. To overcome the shortcomings of the existing methods of reducing pitch moment differences which use adjustable nozzles, a nozzle Model B based on controllable expansion degree distribution is presented in this paper. Model B compares with baseline Model A. Cold-flow test and numerical simulation are conducted on the sub-scaled Model B, and their results agree well with each other. The results demonstrate that at flight Mach numbers 4.5 and 6.5, the pitch moment of the cold-state and hot-state of Model B decreases by 80.49% and 12.73% respectively, while the thrust coefficient decreases by 0.1% at flight Mach number 4.5 and increases by 1.1% at flight number 6.5. The pitch moment performance of the SERN is improved significantly, which effectively reduces the difficulty of the aircraft trim. The validity of the design thinking and method is fully verified, which provides a new approach for improving the pitch moment performance of the SERN.