Numerical simulations of detonation diffraction and re-initiation in ethylene-air mixtures

When a confined detonation propagates over an obstacle, the reaction front experiences an abrupt area change. This leads to detonation diffraction, which allows expansion waves to propagate into the reaction zone. These expansion waves slow the reaction front, causing it to decouple from the leading shock. This may lead to complete detonation quenching or re-initiation, depending on the geometry of the channel and obstacle. An understanding of the fluid dynamics behind this process can lead to improved designs of process safety equipment in transport and storage of hydrocarbon mixtures. We study the diffraction and re-initiation phenomena for ethylene-air mixtures using AMRFCT, a numerical simulation model that solves the multidimensional, reacting flow conservation equations with a chemical-diffusive model (CDM) for conversion of fuel to products with energy release. High-fidelity computations varying the obstacle geometry are used to study the effects of these phenomena on the reaction rates, detonation velocity and cellular structure.