Extinction of Hydrogen Premixed Flames by Turbulence

氢气预混火焰的湍流熄灭

• 批准号: 09650255
• 负责人: YOSHIDA Akira
• 金额: $ 1.54万
• 依托单位: TOKYO DENKI UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650255/
• 关键词: Hydrogen; Counterflow Flame; Extinction; Premixed Flame; Lewis Number; Stagnation Flow; Turbulent Flame; Flame Stretch; 対向流火災; 予混合火災; 乱流火災; 火災伸長; 水素燃焼; ルイス教; レーザー流速計; 対向流バ-ナ; 多孔質円筒

Hydrogen is the promising fuel for future. The characteristic feature of he hydrogen-air premixed flame was investigated using the counterflow burner. The hydrogen-air mixtures within the inflammability limits were ejected from the porous cylinder. The hydrogen-air mixture of same equivalence ratio and uniform velocity distribution from the conversing nozzle was supplied from the bottom. The stable double flame was produced in the stagnation region of the impinging flowfield. In the present study, the flame produced in the counterflow were investigated the extinction mechanism of laminar hydrogen-air flame by varuing the equivalence ratio and the effect of the turbulence on the extinction phenomenon.It was made clear that the large amount of the hydrogen is needed to extinguish the hydrogen-air flame by flame stretch only. Therefore the hydrogen fuel is diluted by the nitrogen and we constructed the nitrogen supply system to extinguish the hydrogen-air flame at small amount of the hydr … More ogen. Firstly, the fuel was diluted by 85% with nitrogen. As a result, on the lean side the extinction limit at which the flame was extinguished increases with the equivalence ratio and the maximum appeared at the equivalence ratio of 1.0. The distance of the upper and lower flame decreased and extinction limit appears due to the incomplete combustion and heat loss. On the other hand, for the rich flames the extinction limit decreases again. The distance between two flames is far even at the state of extinction and extinction occurs only due to flame stretch. Therefore the Lewis number is the important parameter for flame extinction.We were intended to involve the effect of turbulence on flame extinction. However, it was very time consuming to construct the hydrogen and nitrogen supply system and flow controlling system. So the effect of turbulence on the flame extinction could not measure in the present study. However, we have establised the procedure of experiments of dangerous hydrogen-air mixture. Less

氢是未来有前途的燃料。利用逆流燃烧器研究了氢-空气预混火焰的特性。可燃极限内的氢气-空气混合物从多孔圆筒中喷出。相同当量比、均匀速度分布的氢气-空气混合物从转换喷嘴由底部供给。冲击流场的停滞区产生稳定的双火焰。本研究通过改变当量比和湍流对熄灭现象的影响，研究了逆流中产生的层流氢气-空气火焰的熄灭机理，明确了仅通过火焰拉伸来熄灭氢气-空气火焰需要大量的氢气。因此，氢燃料被氮气稀释，我们构建了氮气供应系统，以少量的氢气熄灭氢-空气火焰。首先，用氮气将燃料稀释85%。结果，在稀侧，火焰熄灭的熄灭极限随着当量比的增加而增加，并且在当量比为1.0时出现最大值。由于燃烧不完全和热量损失，上下火焰距离减小，出现熄灭极限。另一方面，对于浓火焰，熄灭极限再次降低。即使在熄灭状态下，两火焰之间的距离也很远，仅由于火焰拉伸而发生熄灭。因此路易斯数是火焰熄灭的重要参数。我们的目的是涉及湍流对火焰熄灭的影响。然而，氢氮供应系统和流量控制系统的建设非常耗时。因此，本研究无法测量湍流对火焰熄灭的影响。然而，我们已经建立了危险的氢气-空气混合物的实验程序。较少的