基于直扩流道构型的RBCC发动机亚燃模态高效燃烧组织研究

Research on Ramjet-Mode Combustion Organization Based on Constant-Expansion Area Configuration in RBCC Combustor

关键词:  火箭基组合循环  亚燃模态  燃烧组织  热力喉道 

Key words:  Rocket based combined cycle  Ramjet mode, Combustion organization  Thermal throat

摘要:

针对支板喷注煤油和一次火箭引导燃烧的RBCC发动机,在亚燃模态下的高效燃烧组织和性能开展了实验研究和数值分析。实验验证了在亚燃模态低来流总温条件下,使用小流量富燃一次火箭产生的高温射流作为引导火焰,可以实现支板喷注二次燃料的可靠点火和高效稳定燃烧。通过数值模拟获得了燃烧室的详细流场特征和燃烧组织细节,分析表明支板后方集中的燃料热释放可形成扩张燃烧室流道中的“热力壅塞”；通过热力喉道的控制,实现了在直扩流道内的高效燃烧。研究表明:发动机在亚燃模态下燃烧组织应尽可能地使热力喉道处于燃烧室较后位置,使燃料在燃烧室高压区内充分燃烧释热,从而提高其燃烧效率。论文还研究了燃料支板喷注位置的影响,进一步开展RBCC发动机亚燃模态性能的优化。 

Abstract:

The experimental and numerical investigations on the combustion organization and performance evaluation of RBCC combustor based on strut injection and primary rocket piloting combustion under ramjet mode have been performed. The experiment shows that the reliable ignition and stable combustion of secondary kerosene fuel by using fuel-rich primary rocket plume as piloting flame have been accomplished under the low total temperature of incoming airflow condition at ramjet mode. Moreover, the CFD simulation has been employed to obtain the detailed information of flowfield characteristics and combustion organization in RBCC combustor, and the results indicate that the thermal coking in the expansion flowpath has been formed due to the concentrated heat release behind the strut injectors. Reasonable heat release distribution along the combustor is important to get better performance. In order to achieve high combustion efficiency, the ‘thermal throat’ should be located on the rear of the combustor which leads to sufficient heat release by fuel combustion. Furthermore, based on current RBCC combustor configuration, the effects of the position of fuel strut injector have been investigated and the performance optimizations have been conducted.