基于气化煤油喷注的RBCC燃烧室亚燃模态燃烧组织研究

Research on Ramjet-Mode Combustion Organization by Using Vaporized Kerosene Injection in RBCC Combustor

关键词:  火箭基组合循环  亚燃模态  燃烧组织  气化煤油喷注 

Key words:  Rocket-based combined cycle  Ramjet mode  Combustion organization  Vaporized kerosene injection

摘要:

针对RBCC发动机亚燃模态进行主动冷却的情况下,煤油发生气化后喷入燃烧室的燃烧组织开展研究。在亚燃模态低来流总温条件下,使用小流量富燃一次火箭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稳定燃烧,当煤油喷注前加热到气化/超临界态时,燃烧室最高压力相比于室温液态煤油提高约10%左右。当关闭一次火箭后,利用凹腔成功实现火焰稳定,而使用室温液态煤油喷注时,凹腔内无法实现火焰稳定。通过数值模拟获得了不同喷注方案的燃烧室燃烧流场特征和燃烧组织过程,为进一步优化燃烧室的性能提供依据。结果分析表明通过合理布置燃料支板喷注位置,由燃料支板下游集中的燃料热释放使得气流在扩张燃烧室构型中实现“热力壅塞”,通过燃料分配实现燃烧室内合理的燃烧释热分布,使RBCC发动机亚燃模态完成高效燃烧组织。 

Abstract:

Considering the active cooling requirement of RBCC engine under ramjet mode, researches on combustion organization based on vaporized kerosene injection in RBCC combustor have been performed. Under the low total temperature of incoming airflow condition at ramjet mode, the reliable ignition and stable combustion of secondary kerosene fuel by using low mass flowrate fuel-rich primary rocket plume as piloting flame has been accomplished. Moreover, the peak pressure in the combustor by injecting supercritical kerosene increased about 10% in comparison of room temperature kerosene. Meanwhile, when primary rocket was closed, flameholding was only achieved by using supercritical kerosene injection. The CFD simulation has been employed to obtain the detailed information of flowfield characteristics and combustion organization in RBCC combustor under different fuel injection strategies, which provides fundamental basis for further optimizing engine performance. 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 by changing fuel split is important to achieve high combustion efficiency. 