细水雾抑制小尺度甲烷/空气火焰的研究

利用三维激光粒子动态分析仪(LDV/APV系统)测量距离同轴流动燃烧装置Cup Burner出口不同位置的细水雾雾场特性(雾滴速度、雾滴粒径),利用Cup Burner系统地研究了细水雾抑制小尺度CH₄/空气顺流非预混火焰,考察细水雾的粒径和雾滴质量分数对CH₄/空气顺流非预混火焰结构的影响. 研究结果表明粒径为10～100 μm的细水雾能有效地抑制CH₄/空气顺流非预混火焰,随着细水雾粒径减小或空气流中雾滴质量分数的增加,细水雾抑制熄灭CH₄/空气顺流非预混火焰的能力增强. 细水雾抑制熄灭CH₄/空气顺流非预混火焰的机理主要是气相吸热冷却和稀释氧气,在CH₄/空气顺流非预混火焰的根部,气相吸热冷却起主导作用,而在火焰的上部稀释氧气起主导作用. 

Experimental Study of Water Mist Suppressing CH4/Air Flame in Cup-Burner

Water mist for fire suppression and control has received considerable attention as one of the potential measures for replacing HALON. Information on volume mean diameter and coordinate component velocity of two types of water mist has been obtained by using LDA/APV system and the mechanism of fire suppression using water mist been explored with the aid of Cup Burner system. A series of experimental study has been conducted to observe the effectiveness of CH₄/air fire suppression using water mist. The results show that water mist consisting of 10～100 μm diameter droplets is an effective flame suppressant in a co-flow cup burner flame. The diameter and mass fraction of water mist significantly affect the temperature distribution of the methane CH₄/air flame. The effect of oxygen dilution is more prominent in the upper part of the flame, whereas, endothermic heat exchange with the droplets plays a critical role in the lower half of the diffusion flame.