Numerical modeling of combustion processes induced by a supersonic conical blunt body

Abstract

The structure of standing oblique detonations around a blunt conical body is numerically studied. A large range of incoming flow velocities and tip radii are compared. The mixture studied is a stoichiometric hydrogen-air at 0.1 atm. The physical model includes a detailed full-chemistry mechanism for the reaction rates. The numerical model is based on a TVD upwind algorithm including a point-implicit finite difference scheme for the coupling between the flow equations and the chemical reaction equations. The characteristics of the detonation induced by the present axisymmetric holder show substantial differences from previous studies performed on oblique detonations supported by a two-dimensional blunted wedge. As the incoming Mach number increases, one can observed the transition from a completely decoupled shock/reaction to a fully-coupled detonation front. When the tip radius of the cone is small, the transition process occurs on a continuous and smooth way along the conical wall of the holder, in contrast with the unsteady structure that develops when the tip radius is large. In a limited range of incoming Mach numbers, we found that the leading shock is able to ignite a strong forward-running detonation from the back of the computational domain. In that case, a forward-running detonation wave supported by a Mach-reflection-configuration has a normal portion that can be interpreted as a strong detonation.