液体火箭发动机喷管流动特性及高度补偿研究进展

喷管作为液体火箭发动机产生推力的重要组件之一,其内部存在的复杂流动现象对发动机性能具有重要影响,本文综述了该领域的相关研究进展。传统喷管在过膨胀状态下会产生自由激波和受限激波两种分离模式,其非定常、非对称性给发动机带来严重的侧向载荷,也造成流动预测较为困难。采用凹坑或涡轮废气主动射流等方式能够避免受限激波分离的出现,抑制侧向载荷,但却无法对喷管损失的性能进行有效补偿。通过对传统喷管的创新设计,高度补偿喷管不仅能够有效控制管内流动,还能在不同程度上提升发动机性能。然而,高度补偿喷管形式众多、各有所长,工程应用应谨慎决策。此外,各种形式的高度补偿喷管内仍旧存在激波/边界层干扰、分离、回流等不利的流动现象,亟待对其开展深入研究。

Progress of Flow Characteristics and Altitude Compensation in Liquid Rocket Engine Nozzle

Nozzle is one of the important component of the liquid rocket engine that mainly produces thrust, complex flows of which have significant impact on the engine performance. The related research achievements in this field are reviewed. Under over-expanded condition, two distinctive flow separation phenomena of free shock and restricted shock separation are existed in conventional nozzles, which are unsteady and asymmetry, bring dramatic side loads to engine, and also make flow predicting more difficult. By using cavity or turbine exhaust gas injector, the restricted shock separation in conventional nozzle is avoided, and the side loads are limited, but lost performance are not effectively compensated. By innovatively designing conventional nozzle contours, altitude compensative nozzle can not only effectively control separation flow in conventional nozzle, but also improve the engine performance in varying degrees. However, there are so many types of altitude compensative nozzles which have its own strong points, applying them to engine should be carefully decided. Furthermore, harmful flow phenomena such as shock wave/boundary layer interaction, separation and recirculation are still existed in altitude compensative nozzles, which are needed to be deeply investigated in the future.