HYBRID DETONATIONS IN OATS DUST CLOUDS IN METHANE-AIR MIXTURES

Detonation waves in oats dust clouds in methane-air mixtures were inve stigated experimentally. Tests were carried out in a vertical tube 4.5 m long with an 8 cm internal diameter. The hybrid mixture was ignited by a shock wave generated by means of the detonation of an oxygen-hydr ogen stoichiometric mixture in the driver section. Flame propagation w as recorded with the use of a streak camera and pressure profiles were measured at selected tube positions. It was found that hybrid detonat ions are possible in oats dust clouds in methane-air ixtures for a ran ge of methane concentrations from 8.5% to 14.5%, with oats dust concen trations not greater than 0.1 kg/m(3). Moderate concentrations of oats dust were found to promote transition to detonation, but this depends on the composition of the gaseous mixture; higher concentrations act as a suppressant.