超细活性及惰性粉体对甲烷/空气预混物层流火焰传播的影响

开展了施加超细惰性SiO_2及活性NaHCO_3粉体对甲烷/空气预混物爆炸层流火焰传播影响的研究,利用高速摄像及纹影系统为主要手段,探究了火焰微观结构及全程火焰传播速度的变化,以及爆炸压力增长进程等参数的变化趋势。结果表明,添加少量SiO_2超细粉体后,火焰传播得以强化,粉体施加量为50 g/m~3量级时,火焰传播速度增长近1倍,提高粉体浓度,其物理作用的抑制效能方能逐步体现,粉体施加量提高到150 g/m~3时,对火焰扰动导致的燃烧强化与吸热抑制作用可相抵消。而施加超细NaHCO_3粉体后,传播速度得以明显抑制,火焰阵面被分割成蜂窝状,抑制程度与施加量成正比,当NaHCO_3的质量浓度达到150 g/m~3时,能够将爆炸火焰完全抑制。施加超细NaHCO_3粉体后,爆炸压力的增长进程明显减缓,而施加超细惰性SiO_2对爆炸压力的抑制效能并不显著。

Interaction of ultrafine chemical active and inert powder with premixed laminar flame of methane-air mixtures

The effects of ultrafine chemical inert SiO2 and active NaHCO3 powder on the premixed laminar flame of methane-air mixtures were studied experimentally.High speed camera and schlieren system were applied to investigate the flame microstructure and variation of flame propagation.Also，the history of explosion overpressure was probed.Results indicate that the flame propagation is enhanced by the turbulence when a small amount of ultrafine SiO2 powder is added，with the concentration of ultrafine SiO2 powder in the order of 50 g/m3，the flame propagation velocity is enhanced 100%，and the effect of physical flame propagation mitigation is appeared gradually with the increase of concentration of SiO2 powder.Flame propagation velocity is suppressed significantly with the addition of ultrafine NaHCO3 powder，and the flame front is divided into honeycomb，the degree of suppression is proportional to the NaHCO3 powder concentration，and the explosion flame is suppressed completely with the concentration of ultrafine NaHCO3 powder in the order of 150 g/m3.Compared to the addition of SiO2 powder，the explosion overpressure increase is slowed down significantly when NaHCO3 powder is added into the methane-air mixtures.