中文摘要：

针对同向和反向合成气旋流扩散火焰燃烧开展研究，测量了燃烧中间产物OH自由基浓度、火焰温度及污染物的排放。实验结果表明，燃烧的稳定性受旋流产生的回流区和扩散混合两方面的因素控制，加强回流有利于燃烧稳定，加强混合也有利于燃烧稳定。燃料和空气同向旋流和反向旋流相比，总回流量较大，能够向回流区卷吸更多的活性自由基OH和热量，从而有利于燃烧稳定。当燃料和空气的旋流数比较小时，混合对燃烧的稳定性也会产生重要影响，空气和燃料的反向旋流由于混合较为强烈从而稳定性比空气和燃料同向旋流时要好。尽管NOx排放受混合的影响，但针对文中的实验，主要是热力型机理对NOx的排放起作用。在CO排放中，较低功率下由于温度较低导致CO排放指数较高，实验中当功率大于34kW时，温度较高，CO排放接近于零。

英文摘要：

The diluted syngas diffuse swirl flame was studied. The OH radical, the flame temperature and the pollutant emission was individually analyzed. The results show that the combustion stability of diffuse swirl flame is controlled by the recirculation and diffuse mixture. The enhancement of the recirculation or the diffuse mixture can be favorable to the combustion stability. Comparing the counter-swirl, the co-swirl of fuel and air has more OH radical and heat is taken to the recirculation zone, thus this is favorable to the combustion stability. When the swirl number of fuel and air is small, mixture is important to the combustion stability. For counter-swirl of fuel and air, the flame is more stable than that for co-swirl more intense mixture. Although the NOx emission is influenced by the diffuse mixture, the thermal mechanism is the main factor for the NOx emission in this experiment. For the CO emission, there are larger index of CO emission when the power of flame is lower due to its lower temperature. In this experiment, the CO emission is near to zone when the flame power is larger than 34 kW.