Acta Astronautica | 2021
Effect of reactive gas mixture distributions on the flame evolution in shock accelerated flow
Abstract
Abstract Flame evolution in shock accelerated flow is studied numerically for an C2H4/3O2/4N2 gas mixture based on the Navier-Stokes equations with a single-step chemistry, and four different distributions of the reactive gas mixture are modelled by the variation of the mass fraction of the fresh reactive gas. The amount of reactive gas mixture increases from case 1 to case 4, and the combustion intensities also increase sequentially. It can be found that the different reactive gas mixture distributions significantly affect the flame evolution in shock accelerated flow. A distinct shock bifurcation emerges in cases 1 and 2. The top and bottom shock bifurcation structures are basically symmetrical about y\u202f=\u202f0.038\u202fm in case 1, but the symmetry between the bifurcation structures is destroyed in case 2 because the flame in the top shock bifurcation zone is closer to the bifurcated shock wave. For cases 3 and 4, a detonation process emerges, and the location and time at which the detonation is initiated vary in each case. The propagation process and final morphology of the detonation wave are also different in cases 3 and 4. From the view of quantitative analyses, the flame area and total heat release rate increase from case 1 to case 4, especially for the time period behind the reflected shock wave. Additionally, the mixing rate increases from case 1 to case 4 before the reflected shock wave interacts with the distorted flame. The mixing rate then decreases sharply in cases 3 and 4 due to the emerging detonation.