Fundamental Properties of Flames Propagating in Starch Dust-Air Mixtures

Abstract

Propagation of starch-dust air flames has been investigated in a tube (3 m long; square cross section 0.2 m × 0.2 m). Laminar, cellular and slightly turbulent propagation regimes have been observed. Several analogies with premixed gaseous flames have been displayed. Conduction heat transfer through the flame appears to be predominant for preheating the mixture. The burning of the mixture occurs in the gas phase after complete pyrolysis of particles. The laminar burning velocity is found equal to 0.27 m/s, the quenching distance 7 mm, the flame thickness 3-4 mm and the lean flammability limit 70g/m³. Some questions, such as the actual role of flame radiation, are not yet completely elucidated.

Keywords:

• flame propagation
• heterogeneous mixture
• dust explosions.