燃油分配对引射模态下RBCC发动机的性能影响

Effect of Fuel Distribution on Performance of RBCC Engine in Ejector Mode

针对RBCC燃油供应系统设计和能量综合利用的问题,采用分析法,研究了不同引射火箭/补燃室燃油分配比例对引射模态下各部件燃油消耗及发动机总体性能的影响。结果表明:补燃室内无二级燃油喷注时,发动机可获得最大推力、比冲和燃油利用率,但此时引射火箭内燃烧过程的不可逆性变大,损失增加,从能量优化利用的角度考虑,为降低发动机中不可逆过程造成的能量损失,建议RBCC在引射火箭燃油分配比例为0.6～0.8的条件下工作;随着引射火箭燃油分配比例的增加,发动机推进效率的增长趋势并不明显,从RBCC优化设计的角度考虑,可适当降低一级引射火箭燃油分配比例,缩小引射火箭结构尺寸,减小内流道气体流动阻力,避免引射壅塞现象的产生,有利于扩宽发动机飞行速域,提高RBCC工作模态综合性能。

Aiming at the design of fuel supply system and energy comprehensive utilization of RBCC engine, with the method of exergy analysis, the influence of the fuel distribution on the fuel consumption of main components and engine performance during ejector mode was investigated. The results show that when the afterburning chamber has no secondary fuel injection, the RBCC engine can obtain the maximum thrust, specific impulse and fuel efficiency. However, the exergy loss of the ejector rocket will increase rapidly as a result of larger irreversibility of the combustion process at the same time. From the point of energy optimization utilization, with the purpose of reducing energy loss caused by the irreversible process in the engine, the RBCC is recommended to work in the condition that the proportion of fuel distribution to the ejector rocket is 0.6-0.8. In addition, the propulsive efficiency of RBCC engine goes up slightly with the increase of fuel flow in the ejector rocket. From the perspective of engine optimization design, the proportion of fuel distribution and the size of ejector rocket should be minified appropriately so that the flow resistance can be reduced to avoid the phenomenon of choking in the flow path. It will be helpful to broaden the speed domain of RBCC and improve the engine performance as well.