Shem Lau-Chapdelaine successfully defends his Master's thesis

.. and onto a PhD.

Numerical Simulations of Detonation Re-Initiation Behind an Obstacle

by She-Ming Lau-Chapdelaine 

This numerical study explored the mechanisms responsible for the re-initiation of a detonation, which quenched while diffracting over a half-cylinder obstacle. The purpose of the study was to make accurate predictions of when detonation re-initiation would occur, determine the role various re-initiation mechanisms, and compare the effect of different chemical models.

The problem was modelled using the reactive Euler equations with either the one-step Arrhenius or two-step chain-branching chemical models, calibrated to post-shock conditions in order to properly reproduce the ignition delay. The simulations were validated using the stoichiometric methane-oxygen experiments of Bhattacharjee et al.

Detonation failure and separation into shock-flame structure

The numerical model was able to accurately predict detonation re-initiation conditions found in experiments. There was generally good qualitative and quantitative agreement between experiments and simulations. While the one-step model was sufficient in predicting re-initiation, the two-step model reproduced some of the finer details of the flow field and detonation re-initiation. The study found that Kelvin-Helmholtz and Richtmyer-Meshkov instabilities did not appear to influence detonation re-initiation of the Mach stem. Detonation re-initiation occurred due to adiabatic compression of the Mach stem, or transport of a flame along the wall jet. Transverse detonations were poorly reproduced, possibly because of the absence of proper resolution of Richtmyer-Meshkov instabilities.

Detonation re-initiation

You can find his thesis here.