On the role of turbulence in detonation induced by Mach stem reflection

A series of experiments conducted by Chan has shown that while some shock w aves may not be strong enough to induce detonation when they collide with a n obstacle the resulting Mach stem will induce detonation if it collides wi th a subsequent obstruction. A series of numerical simulations, however, fa iled to demonstrate the expected results if either the Euler or laminar Nav ier-Stokes equations are solved. On the other hand, calculations using the Favre averaged Navier-Stokes equations with a k-epsilon-F turbulence model are able to reproduce the experimental results, indicating that turbulent e ffects may play an important role in the ignition process. A detailed exami nation of the results shows that turbulence causes the formation of activat ed kernels in a similar process to that observed in deflagration-detonation transition. The simulations in this paper have been undertaken using a mod em high resolution hydrocode and a reduced kinetics mechanism for hydrogen combustion. The paper describes the reduced mechanism, the solution methods employed in the hydrocode and discusses the results of the simulations and their implications.