Combustion and detonation of propane–air compositions in large-scale experiments

This paper presents the results of two large-scale tests performed to clarify the conditions for the detonation of propane–air compositions in model surface clouds in the absence and in the presence of confining rigid walls. Model clouds with dimensions of 15 × 6 × 4.2 and 15 × 6 × 2 m were confined by plastic tents. A mixture of the starting reagents in the cloud was ignited by hot detonation products propagating along a perforated o0.82 × 23 m tube passing through the space of the tent. Hot detonation products were injected from the tube through holes of 20 and 40 mm diameters. Detonation of the propane-air mixture in the tube was initiated by explosion of an explosive charge placed at the tube end. Detonation occurred in the propane–air cloud bounded on one side by a rigid vertical wall, and no detonation was observed in the cloud with similar injection of hot products without a rigid wall. It is concluded that the divergence or convergence of the flows of hot detonation products plays a key role in the process, being responsible for the presence or absence of detonation, respectively, in the mixing region.