Wedge-stabilized oblique detonation in an inhomogeneous hydrogen-air mixture

We performed numerical simulation against oblique detonation formed in an inhomogeneous hydrogen-air mixture. Planar two-dimensional Navier-Stokes equations were solved with the chemical source terms calculated with a detailed chemical kinetics including 9 species and 27 elementary reactions. Fuel concentration gradients described by the Gaussian function were introduced into two different conditions: (A) a Mach 8 flow onto a 28.20 degrees wedge with a static pressure of 8.50 kPa, and (B) a Mach 8 flow onto a 23.8 degrees wedge with a static pressure of 34.0 kPa. Fuel-rich conditions on the centerline generated V-shaped deflagration front under the former condition, and V + Y Mach stem under the latter due to the strong concentration gradients near the surface. These shapes caused a couple of triple points to appear on the incident shock front. Transition to detonation occurred twice along the front in some cases. The apex of V-shape was always located in a similar position due to almost constant thermochemical properties of the incoming streamline. The threshold for emergence of these V-shapes can be reasonably attained by the magnitude of induction length gradient close to the wedge. (C) 2016 by The Combustion Institute. Published by Elsevier Inc.