"Predictability of detonation wave phenomena: influence of diffusive processes, hydrodynamic instabilities and relaxation effects on the hydrodynamic description"

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Detonation waves are self-sustained supersonic reaction waves, which can be sustained in reactive gases and condensed phase energetic materials (propellants, explosives, dusts, etc...). The large overpressures occurring behind gaseous detonations make them useful for propulsion applications. These applications require accurate control of the wave initiation and wave stability. For safety applications, whenever a detonable gas is accidentally released, it is desirable to have the capability for predicting the eventual ignition and propagation limits and the large-scale effects in order to develop the appropriate mitigation strategies. Unfortunately, the detonation wave dynamics cannot be predicted in typical engineering applications. The present research's objective is to develop such a predictive model. To arrive at this modeling capability, we proceed in two steps. First, the small-scale physical phenomena occurring within the detonation structure, which control the rate of energy release, are investigated using a novel experimental technique. This technique isolates in well-posed reproducible experiments the canonical feature of detonations waves, namely the reactive triple shock configuration. Simultaneous high-fidelity numerical simulations of this phenomenon permit us to quantify the various physical instabilities governing the local and global rates of exothermicity. Secondly, we formulate and test the appropriate reaction zone models that will permit us to conduct engineering calculations and predict detonation phenomena with sufficient fidelity at user scales, which are typically more than six orders of magnitude larger than reaction zone instabilities. These models are obtained by mathematically formulating the physical observations observed in the experiments at small scales and calibrating them against critical experiments.