Statistical Analysis of Transverse Wave Speed in Near-Limit Hydrocarbon Detonations

This work details the statistical characterization of transverse wave speeds in propagating hydrocarbon detonations. Detonation wave behavior is characterized by the presence and interaction of shock waves traveling normally to the detonation front. These interactions lead to the cellular nature of the detonation. Fundamental understanding of the behavior of these transverse waves in needed to fully understand the propagation and sustaining mechanism of the detonation. A fully automated quasi-2D detonation facility was utilized to build a large dataset of detonation data across 240 realizations of methane-oxygen mixtures diluted with nitrogen. Simultaneous 10MHz shadowgraph imaging and 5MHz CH* chemiluminescence imaging is used to track the evolution of the shock wave structure and the coupling of the reaction front. Comparing the relative velocities of the transverse waves to the local wavefront gives insight into the regularity of the detonation. As the detonation limit is approached, the relative speed of the transverse waves decreases while the variance greatly increases. This indicates the reliance of the detonation on the presence of transverse detonations to self-sustain