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为了设计火焰更加稳定的燃烧器,需要对导致火焰不稳定的机理开展研究。通过在钝体外侧通环形空气流,中心通燃料得到钝体稳燃非预混火焰。借助平面激光测速仪、增强型光电耦合器等测量手段,对两类不稳定火焰——不稳定脱离火焰和分离闪烁火焰的流动和反应区分布进行了测量,分析了导致两类不稳定火焰机理。结果发现,中心燃料和空气雷诺数的相对大小不同的情况,进入回流区内的燃料量的差异,是导致出现不同不稳定火焰模态的重要机制。因此为了得到稳定的钝体燃烧器中心射流火焰,需要合理安排流场使得回流区内燃料浓度合理。
In order to design a burner with a more stable flame, a study has to be done on the mechanism that causes the flame to be unstable. Through the outer side of the bluff body through the annular air flow, the center of the fuel to be blunt-body stable non-premixed flame combustion. By means of measurement of planar laser velocimeter and enhanced optocoupler, the flow and reaction zone distributions of two kinds of unstable flame - unstable detachment flames and separation flames were measured. Two kinds of unstable flame mechanisms . It is found that the difference in the relative sizes of the central fuel and air Reynolds numbers and the difference in the amount of fuel entering the recirculation zone are important mechanisms that lead to different unstable flame modes. Therefore, in order to obtain a stable bluff body burner center jet flame, the flow field needs to be reasonably arranged so that the fuel concentration in the recirculation zone is reasonable.