分级双旋流高温升燃烧室贫油熄火特性研究

Lean blowout (LBO) is a major technical challenge maintain the efficiency, reliability and performance for high temperature rise combustion in gas turbine engines. Currently, the allowable operating conditions during power transients of the engine are constrained by the LBO margin. Reduction in this margin can potentially result in lower pollutant emissions and enable faster engine transients. Lean direct injection combustion presents a method to burn fuel at lower temperatures and reduce NOx emissions. For an engine designer, the challenge is to develop a combustor that achieves stable operation and low emissions over the full range of engine conditions. This requires the combustor designer to build sufficient margin into the design to prevent LBO at the worst case operating condition. Consequently, there can be an increase in NOx production compared to what could be optimally achieved at other operating conditions..This study presents an LBO mitigation design and experiment schemes replete with staging/double swirler in a direct injection combustor approaches. The objective is to stabilize a lean direct injection flame by increasing the safety margin, and to obtain the solution method of the contradiction between of LBO in the ground idle and smoke exhaust in the case of take off, and to establish the LBO discipline of staging/double swirler in a direct injection combustor.Finally, the coupling and expressions of increasing the LBO safety margin with different parameters to can be summarized In this study, the experimental investigation conducts for the fuel staging combustor with two domes to improve the LBO fuel air ratio. To avoid blowout, redistribution of the total fuel inside the combustor between main and pilot nozzles has been used, the injected fuel between the main swirl injector and a direct mixing, pilot injector that supplies fuel to the flame stabilization region.The idea is to increase the equivalence ratio near the stabilization region of the combustor and provide a locally more stable combustion zone that can anchor the flame in the rest of the combustor. This moves the effective LBO limit to leaner overall mixtures, thus increasing the LBO safety margin.

通过对采用分级燃烧组织方式的高温升燃烧室进行贫油熄火特性实验测试，获得慢车工况下分级燃烧设计对扩展整个燃烧室贫油熄火边界及改善冒烟的效果及规律，揭示不同燃烧参数对拓宽贫油熄火边界的多因素耦合关系，获得修正后的具有良好适用性的高温升燃烧室的慢车贫油熄火模型，为高性能航空发动机燃烧室稳定燃烧与熄火智能控制研究提供理论支持。掌握解决在慢车状态下贫油熄火和在大工况下不可见排气冒烟矛盾的解决途径和方法，拟建立分级双旋流高温升燃烧室组织燃烧技术对慢车贫油熄火规律，揭示不同燃烧参数对拓宽贫油熄火边界的多因素耦合关系，总结出高温升燃烧室贫油熄火关系式，得到具有良好适用性的贫油熄火油气比的模型。

针对高温升燃烧室在慢车状态下贫油熄火和大工况下不可见排气冒烟这一基本矛盾，本项目开展燃烧室头部的气流组织、燃油雾化以及与空气的混合对高温升燃烧室慢车工况下贫油熄火影响机理开展研究工作，建立了主模与副模燃烧区同心圆式分布的燃烧头部组织结构模型，并设计了同、反向两种旋流器结构，采用了无主燃孔、无掺混孔的发散小孔冷却的燃烧室室壁结构，建立单管燃烧室模型进行数值模拟研究。计算慢车和设计工况获得了燃烧室的速度场特性和温度场特性，并通过对同向旋流和反向旋流贫油熄火极限的比较来说明燃烧室头部流场与雾化对喷油熄火的影响。试验测试了中心分级单管燃烧室贫油熄火性能，获得慢车工况下分级燃烧设计对扩展整个燃烧室贫油熄火边界及改善冒烟的效果及规律，揭示不同燃烧参数对拓宽贫油熄火边界的多因素耦合关系。