NH_4H_2PO_4和SiO_2粉体对铝粉火焰传播特性的影响

Effects of NH_4H_2PO_4 and SiO_2 power on propagation characteristics of aluminum dust flame

为探索受限空间内惰性粉体对铝粉火焰结构及火焰传播特性的影响机制,利用小尺寸开口竖直管道和高速摄影仪和微细热电偶,研究添加质量分数为20%的NH_4H_2PO_4和SiO_2粉体时铝粉燃烧火焰形态、火焰温度和火焰传播速度等参数的分布特征。结果表明:NH_4H_2PO_4和SiO_2粉体能稀释铝粉尘云浓度,有效减弱反应强度;铝粉粒径增大,惰性粉体对铝粉最高火焰温度的抑制作用先增大后减小,当铝粉粒径为30μm时,抑制效果最显著;惰性粉体对铝粉火焰传播速度的抑制作用与铝粉粒径负相关;NH_4H_2PO_4对铝粉火焰的抑制效果比SiO_2明显。

For the sake of exploring the mechanism by which inert powder affects structure and propagation characteristics of aluminium flame in a confined space,experiments were carried out.The flame shape,flame temperature and flame propagation velocity of aluminium flame were measured when 20% mass fraction of NH_4H_2PO_4 and SiO_2 powder were added to by using a small opening vertical pipe,a high-speed camera and a micro thermocouple.The results show that both NH_4H_2PO_4 and SiO_2 powder can dilute the concentration of aluminum powder and weaken the reaction intensity,that with increase of particle size of aluminum powder,the inhibition effect of inert powder on maximum flame temperature of aluminum powder firstly increases and then decreases,and the inhibition effect reaches the maximum when the particle size of aluminum powder is 30 μm,that the inhibition effect of inert powder on flame propagation velocity of aluminum powder is negatively correlated with the particle size of aluminum powder,and that the inhibition effect of NH_4H_2PO_4 powder on aluminum powder flame is more obvious than that of SiO_2.