| Rocket Based Combined Cycle( RBCC) is a very promising propulsion system for the hypersonic missile. RBCC combines the advantages of rocket engine’s high specific impulse and the air-breathing engine’s high specific impulse, having attracted great attention of many countries around the world.The RBCC engine is the first selection of hypersonic aircraft and space transportation system. The RBCC Rocket Ejector Mode has a key role in the take-off stage.This article analizes the relevant factors influencing Ejector Mode by thermodynamic cycle, numerical simulation and experiment.First the passage builds the thermodynamic cycle model of Ejector Mode in theory. Thecomputation’s results show that thrust increases first and then decreases with the increase of the ejector coefficient. There exists an optimum ejector coefficient where thrust ratio is biggest. Increasing total pressure and decreasing total temperature benifit thrust augmentation.It is very important to decrease th e mixing loss in the mixer.Secondly numerical simulation is used to investigate the ejector mode. The results show that the injecedt air mass flow will become bigger when rocket total pressure increases. If the rocket total pressure continues to increase,the injecedt a ir mass flow will decrease. The possition of oil has less important influence on ejector coefficient and thrust. When the radium of the engine exit decreases,the ejector coefficient will decrease. But the velocity of exit will increase.The length of mixer help increase ejector coefficient but has a limited influence.For experiment part, the RBCC model is designed and finished.The experimental results show that When the primary flow is very small, the injecedt air mass flow is also very small. But the primary flow increases, the pressure rise in the engine is very obvious. The length of mixer has a very limited onfluence on injecedt air mass flow.However, When the length of mixer increases, it helps mixing enhancement. |
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