构型及二次燃烧对RBCC引射模态推力性能的影响

Effects of configuration and secondary combustion on RBCC thrust in ejecting mode

提出了掺混度模型并数值研究了五种构型和两种燃烧组织模式对RBCC发动机引射模态推力性能的影响,其中改进构型获得了推力增强。得出如下结论:(1)在引射掺混的前段,掺混过程主要由一次流喷管结构决定。而在引射掺混后段,后体构型对掺混过程影响较大。(2)获得较高掺混速率、较优引射比并在掺混过程中产生高于环境压强的流动状态是改进构型获得推力增强的两个重要因素。(3)与SMC燃烧组织模式相比,改进构型的SPI模式有效延迟了二次燃烧,不仅提高了燃烧效率而且没有使引射比过度下降。

3D mixing and reacting flows of five RBCC configurations with two secondary combustion organization methods in ejecting mode were investigated with numerical techniques and newly established mixing degree model. In those configurations only the improved configuration obtained the thrust augmentation. It is concluded that: (1) The first mixing process of supersonic primary flow and subsonic ejected flow are mainly affected by the primary nozzle geometry; while in downstream mixing the mixer configuration plays a more important role. (2) High mixing rate, optimized entrainment ratio and higher mixed static pressure than ambient pressure are two key elements to get thrust augmentation of the improved configuration. (3) Compared with SMC (Simultaneous Mixing and Combustion), SPI (Shielded Primary Injection) method used by improved configuration effectively delays secondary combustion and avoid excessively decreasing of entrainment ratio.