Dynamics of an Explosion-Driven Planar Exothermic Jet

Considered here is combustion of an explosion-driven turbulent jet in a thin cylindrical enclosure. The process is initiated in a small pre-chamber, filled with acetylene mixed with 10% air, and provided with an explosive igniter charge. The prechamber is connected to the main enclosure, filled with air at NTP, by sealed orifice. Upon ignition of the explosive charge, the acetylene is thermally decomposed, generating a detonation in the pre-chamber. The high pressure thus engendered breaks the seal and creates a blast wave that injects the fuel jet into the main enclosure which undergoes then an exothermic process of combustion with air. The mixing layer is repeatedly compressed and expanded due to blast wave reverberations within the enclosure. Experimental results, in the form of cinematic shadow photographs and transient pressure records, are modeled by a two-dimensional CFD analysis of combustion dominated by turbulent mixing. The results reveal the dynamic features of turbulent combustion when the exothermicity is controlled by fluid-mechanic transport in a turbulent field, rather than by the effects of the exothermic reaction and diffusion, that is usually the case.