Extinction of Hydrogen Premixed Flames by Turbulence

氢是未来有前途的燃料。采用逆流燃烧器研究了氢气-空气预混火焰的特性。在可燃极限内的氢-空气混合物从多孔圆筒中喷出。由转换喷嘴喷出的等当量比、速度分布均匀的氢气-空气混合气从底部供给。在冲击流场的滞止区产生了稳定的双火焰。本文通过改变当量比和湍流度对火焰熄灭现象的影响，研究了氢气-空气层流火焰在逆流中产生的火焰熄灭机理，明确了氢气-空气层流火焰的熄灭需要大量的氢气才能通过火焰拉伸来实现。为此，我们设计了一套氮气供应系统，通过氮气稀释氢燃料，使氢-空气火焰在少量氢气的情况下熄灭。 关于我们 原。首先，用氮气将燃料稀释85%。结果，在贫侧，火焰熄灭的熄灭极限随着当量比而增加，并且在当量比为1.0时出现最大值。由于不完全燃烧和热损失，上、下火焰间距减小，出现熄灭极限。另一方面，对于富火焰，熄灭极限再次降低。即使在熄灭状态下，两个火焰之间的距离也很远，并且熄灭仅由于火焰拉伸而发生。因此，刘易斯数是火焰熄灭的重要参数。然而，氢氮供应系统和流量控制系统的构建非常耗时。因此，湍流对火焰熄灭的影响在本研究中无法测量。但是，我们已经建立了危险的氢-空气混合物的实验程序。少

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