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Hockey Farewell Party - Geoff Maines submitted his thesis and off to Cali

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Geoff and Nick #Canadasgame #odr #doubledion Geoff Maines submitted his Master's thesis.  Given he will miss the Canadian winters from Cali, we organized a group hockey outing.    Wentian in top shape Kadeem and Logan Nick and Shem - Leafs fans Geoff and Karl Maxime and Mama

Our new detonation driven shock tube

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Our new detonation driven shock tube is now up and running.  Modular length, 12 inch internal diameter, rated for atmospheric pressure detonations, modular reactive driver volume, and outfitted with the Yellow Submarine as receptor/dump tank with optical access.  Jonathan Armstrong, its creator

What makes fast flames fast: influence of hydrodynamic instabilities

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We just submitted our new paper on the fast flame supersonic regime in gases. A pre-print , along with the high speed videos , are available on ArXiv. Our work investigates the structure of fast supersonic turbulent flames typically observed as precursors to the onset of detonation. These high speed deflagrations are obtained after the interaction of a detonation wave with cylindrical obstacles. Two mixtures having the same propensity for local hot spot formation were considered, namely hydrogen-oxygen (2H 2 +O 2 ) and methane-oxygen (CH 4 +2O 2 ). We show that the methane mixture sustains turbulent fast flames, while the hydrogen mixture does not. An incident detonation wave in 2H 2 +O 2 coming from the left interacts with a row of cylinders.  The subsequent fast flame, consisting of a system of discrete hot spots and transverse shock system, fails; the figure consists of an overlay of frames showing the evolution; See Video . A supersonic turbulent fast flame is es...

Asymptotically self-similar flows are scarred for life: early injuries in problems of shock reflection and refraction

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Self-similar inviscid flows in gas dynamics abound, e.g., strong Taylor-Sedov blast waves, shock diffraction and reflection at a compressive or expansion corner, and many other shock/shock interactions, shock slip lines interactions. With the neglect of viscous effects and the corresponding dissipation length and time scales, problems of shock dynamics are self-similar.   Simple magnification of the length scales of observation can be obtained at correspondingly scaled evolution times.  In reality, such problems are never self-similar at a young age.  Characteristic length scales exist in these problems, often at the smallest scales (boundary layers, shear layers, shock structure, etc...). Our numerical experiments address how the introduction of small characteristic length scales affect the asymptotically self-similar solution at much later times.  We pose the question: How does an early injury of the self-similar regime affect the solution at later t...

Distinguished Paper Award- Detonations (2013) by the Combustion Institute

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Our paper “ Detonation re-initiation mechanism following the Mach reflection of a quenched detonation ” was selected as the Distinguished Paper in the Detonation colloquium of the 34th International Symposium on Combustion.    Congratulations to Rohit Bhattacharjee, She-Ming Lau-Chapdelaine, Logan Maley and Geoff Maines. Fig. 4 in paper - Re-ignition behind the Mach shock over a rough plate and entrainment of flame in the jet associated with this type of "jetting" Mach reflection.

DRDL @ ICDERS 2013

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Last week, Logan Maley, Hesam Akbarnejad,  Maha Manoubi and myself were attending the ICDERS conference in Taipei, Taiwan. Maha, Matei, Hesam and Logan Structure of high speed deflagrations, DDT and self-generated turbulence Logan presented his study on the structure of supersonic turbulent deflagrations and DDT.  Strong pressure waves are driven by the rapid ignition of hot-spots.  The driven hydrodynamic instabilities along shear layers permit to rapidly burn the gases.  Onset of detonation in a Ch4-O2 high speed deflagration A detonation in the detonation ?  Very similar to self-sustained detonations, just slower.  The session was closed by a panel discussion on DDT.  The concept of self-turbulization of the flame came out as the outstanding theme for future research.  Logan pursued discussions with Joe Shepherd...  Hesam on bimetallic flames Hesam presented his thesis work on the flame speed in bi-metallic mixtu...

Rohit Bhattacharjee successfully defends his Masters thesis - more on detonation structure and Mach shock reflections

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Experimental Investigation of Detonation Re-initiation Mechanisms following a Mach Reflection of a Quenched Detonation by Rohit Ranjan Bhattacharjee Detonation waves are supersonic combustion waves that have a multi-shock front structure followed by a spatially non-uniform reaction zone. During propagation, a decoupled shock-flame complex is periodically re-initiated into an overdriven detonation following a transient Mach reflection process. Past researchers have identified mechanisms that can increase combustion rates and cause localized hotspot re-ignition behind the Mach shock. But due to the small length scales and stochastic behaviour of detonation waves, the important mechanisms that can lead to re-initiation into a detonation requires further clarification.  If a detonation is allowed to diffract behind an obstacle, it can quench to form a decoupled shock-flame complex and if allowed to form a Mach reflection, re-initiation of a detonation can occur. The use of t...

Our work horse...

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