Experimental investigation on suppression of starch flame by ultrafine silicon dioxide powders

It is well known that the ultrafine silicon dioxide powder has a certain suppressing effect on the wheat starch flame. In this work, we explore the difference in this effect on the silicon dioxide powder due to different particle sizes, the changes of flame propagation, temperature, velocity and other parameters of the wheat starch combustion by adding 10 μm and 30 nm silicon dioxide powders. The experimental results show that the ultrafine silicon dioxide powder can reduce the wheat starch's burning reaction strength. The 30 nm powder produces a more effective suppression than the 10 μm powder. When the wheat starch powder's particle size is below 25 μm, The ultra fine powders with a mass concentration of 0.43 kg/m³ and a grain size of 30 nm can significantly decrease the wheat starch's flame brightness, reducing its maximum temperature by 38.07%, its maximum and average velocities by 42.25% and 65.59%, respectively. The ultrafine silicon dioxide exerts mainly an effect of physical suppression, which is inversely proportional to the particle size of wheat starch grains. The smaller the wheat starch grain size, the better the effect of silicon dioxide suppression.