Microscopic Hypersonic Jetting in Oblique Detonation Waves

We present a highly-resolved state-of-the-art 2-D Direct Numerical Simulation (DNS) of a wedge-induced Oblique Detonation Wave (ODW) using a 9-species 21-reaction chemical kinetic mechanism for a H2-air mixture. Adaptive Mesh Refinement (AMR) is leveraged to obtain a resolution of Δx = 0.78μm (which is roughly 20× the mean free path of the fuel-air mixture at the inlet) at the finest level. The finest AMR level spans the ODW front and its transverse waves. The simulation is performed for an extended domain to unravel the different instability patterns observed on the ODW front. This hence marks one of the very few studies in literature that has considered multi-step chemical kinetics for a large domain with a fine resolution for ODW simulation. We capture, for the first time, the onset of microscopic hypersonic jets far downstream of the wedge-tip that lead to cellular instabilities resembling those of a Normal Detonation Wave (NDW). As noted by previous studies on ODW structure, a “psuedo-cellular” zone devoid of the classical NDW triple-points and the micro-jets is also spotted.