Radulescu Gasdynamics Laboratory

The dynamics of cellular detonations are simpler to illustrate using Lagrangian trackers. The video was obtained from a simulation using James Quirk's AMRITA by Bijan Borzou.

Earlier in the week, some of us were in Waterloo, ON, at the Canadian Section of the Combustion Institute yearly technical meeting , where we presented progress in our reactive gasdynamics work. Wentian, Bijan, Nick, Matei, Brian and Mohamed Thermal ignition revisited with molecular dynamics: role of fluctuations in activated collisions N. Sirmas & M.I. Radulescu Nick Sirmas, in true form, presented his study on the role of molecular fluctuations in self-ignition in gases. He tackled thermal ignition problem with molecular dynamics. He found that non-equilibrium effects during thermal runaway occurs via hot-spots.  These are spontaneously generated by molecular fluctuations, and preferred in systems with high activation energies and heat release.  Reactive collisions are preferred in the neighborhood of previous reactive collisions, as common sense dictates.  The result is that at sufficiently low temperatures, hot spots are responsible for drastic r...

Mohamed Saif just completed his MaSc thesis on the CJ deflagrations and their transition to detonation. Also, check out our Proceedings of the Combustion Institute pre-print paper . Run-Up Distance From Deflagration to Detonation In Fast Flames Abstract In the process of deflagration-to-detonation transition (DDT) in reactive gases, the flame typically accelerates first to the choked flame condition (known as a Chapman-Jouguet deflagration), where it propagates at the sound speed with respect to the product gases. Subsequently, the choked flame may transit to a detonation. In the present study, the transition length from choked flames to detonations was measured experimentally in laboratory-scale experiments in methane, ethane, ethylene, acetylene, and propane with oxygen as oxidizer. The choked flames were first generated following the quenching of an incident detonation after its interaction with cylindrical obstacles with two different blockage ratios, 75\% and 90\%. Compari...