RBCC引射/亚燃模态过渡工作过程数值模拟

Numerical simulation for operation process of ejector/ramjet mode transition of RBCC

关键词:  火箭基组合循环(RBCC)  引射模态  亚燃模态  模态过渡  数值模拟

Key words:  Rocket based combined cycle  Ejector mode  Ramjet mode  Mode transition  Numerical simulation

摘要:

针对模态过渡过程中的瞬变特性,开展了引射/亚燃模态过渡工作过程中的RBCC进气道/燃烧室一体化数值模拟,计算比较了四种不同的模态过渡方案,分析了模态过渡工作过程中流动、燃烧模式和进气道状态的瞬变过程,研究结果表明:(1)推力产生较大波动的主要原因是燃烧室内燃烧/流动参数匹配性差和在流动方向上燃烧放热间断引起的;(2)主火箭保留的燃气在模态过渡过程中起到了火焰稳定和自持燃烧的作用,保留合理流量的燃气不仅可以缩短模态过渡时间,而且可以提高发动机的比冲;(3)提出了通过调节燃料喷注策略和主火箭节流方式实现模态平稳过渡的方案,并对该方案进行了数值验证,可望为进一步的实验研究提供了燃烧控制方法。

Abstract:

Four different mode transition scheme integration numerical investigation for combustion flow field of inlet and combustor was carried out. The transformation rule of flow and combustion mode and inlet operation state during the mode transition transient process was investigated. The results show that the main cause of thrust fluctuation is the discontinuity of combustion and heat reaction area along the flow direction and the reserved hot gas of primary rocket plays the role of flame holder and combustion enhancement. Reasonable mass flow rate of the reserved hot gas can not only shorten the mode transition time, but also can improve the specific impulse of RBCC. Based on numerical simulation result the mode smooth transition scheme through modulating the fuel injection scheme and throttling style of primary rocket was brought forward. The mode smooth transition scheme is validated by numerical simulation. The numerical results may provide combustion control method to be used in experiment.