Combustion and detonation of propane–air composition 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 sizes of 15 $\times$ 6 $\times$ 4.2 and 15 $\times$ 6 $\times$ 2 m were confined by plastic tents. A mixture of starting reactants in the cloud was ignited by the hot detonation products propagating along a perforated $\varnothing$ 0.82 $\times$ 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 play a key role in the process, being responsible for the presence or absence of detonation in the mixing region, respectively.