浓度对垂直独头管道玉米淀粉火焰传播的影响

选择真空干燥后的食品级玉米淀粉,利用激光粒度分析仪和扫描电镜分析颗粒的形状和几何尺寸。利用高速摄像机技术,在1.2 m长的垂直独头管道内对玉米淀粉粉尘云的爆炸火焰传播行为进行实验研究,考察有、无障碍物的条件下粉尘云浓度对火焰传播的影响。结果表明:火焰整体上呈先增加再降低的发展趋势。粉尘云浓度和障碍物均对玉米淀粉粉尘云火焰传播形态及火焰速度具有显著影响。随粉尘云浓度增加,粉尘燃烧不充分,导致出现最大火焰速度和火焰亮度均逐渐降低,火焰轮廓不清晰,火焰分段等现象。障碍物的湍流效应会加速粉尘燃烧,增加粉尘火焰传播速度,提高火焰亮度和轮廓清晰度,但粉尘云浓度增加会降低障碍物对火焰传播的加速效应,促使最大火焰速度呈先增加再降低的趋势。

Effect of concentration on flame propagation of cornstarch in vertical half-open pipe

Takingfood grade corn starch after vacuum drying as example, particle shape and sizewere analyzed by laser particle size analyzer and SEM. High speed cameratechnology was used to study explosive flame propagation behavior of cornstarch dust cloud in a 1.2 m long vertical half-open tube, and the influence ofdust cloud concentration on flame propagation with or without obstacle wasinvestigated. The results showed that the flame speed overall increases at firstand then decreases. Both dust cloud concentration and obstacle have significantinfluence on the flame propagation pattern and flame speed of corn starch dustcloud. With the increase of dust cloud concentration, the dust combustion isnot sufficient, resulting in the gradual decrease of the maximum flame speedand flame brightness and unclear flame contour and flame segment phenomenon.The turbulence effect of obstacles will accelerate the combustion of dust,increase the speed of dust flame propagation, improve the flame brightness andcontour clarity. However, an increase in the concentration of dust clouds willreduce the accelerated effect of obstacles on flame propagation, and promotethe maximum flame speed to increase at first and then decrease.