Predictability of detonation wave dynamics in gases: experiment and model development

爆震波是一种自持的超音速燃烧波。这些波可以在包括活性气体在内的大多数高能介质中持续存在。因此，就安全应用而言，在采用不同的减缓策略时，希望能够预测爆震波的最终点燃及其传播极限。同样，爆震波的推进应用（如旋转爆震发动机、脉冲爆震发动机、斜爆震发动机）需要精确控制爆震波的起爆和稳定性。出于所有实际目的，爆轰行为需要在米量级的尺度上进行预测（发动机几何形状、阻爆器、工业设施配置等），而爆轰波厚度现象发生在与分子平均自由程相当的尺度上，即小于一微米。因此，爆轰现象是一个固有的多尺度问题，具有多尺度物理。爆轰波动力学的充分可预测性目前在工程尺度上是不可能的。实现这种可预测性是我对气体爆炸长期研究计划的主要推动力。

Detonation waves are self-sustained supersonic combustion waves. These waves can be sustained in most energetic media including reactive gases. For safety applications, it is thus desirable to have the predictive capability for the eventual ignition of a detonation wave and for its propagation limits when different mitigation strategies are used. Likewise, propulsion applications of detonation waves (e.g., rotating detonation engines, pulse-detonation engine, oblique detonation engine) require accurate control of the wave initiation and stability. For all practical purposes, the detonation behavior needs to be predicted on scales on the order of meters (engine geometry, detonation arrestors, industrial facility configuration, etc...), whereas the detonation wave thickness phenomena occur at scales comparable to the molecular mean free path, i.e. less than a micron. The detonation phenomenon is thus an inherent multi-scale problem, with multi-scale physics. Adequate predictability of detonation wave dynamics is not currently possible at engineering scales. Achieving such predictability is the main thrust of my long-term research program on gaseous detonations. The research program applied for is a state-of-the-art multi-scale experimental and theoretical investigation of the phenomena controlling the reaction rates in detonation waves. Well-posed experiments at various scales of observations (the micro, meso and engineering scales) will permit to formulate and calibrate proposed closure models. At small scales, the influence of non-equilibrium effects and stochasticity stemming from molecular fluctuations will be studied in thermal ignition problems and compared with carefully designed experiments of critical ignition. At the meso-scale, our recently proposed Large Eddy Simulation strategy aimed at properly addressing both auto-ignition and turbulent mixing will be calibrated from the micro-scale experiments and simulations and tested against meso-scale dynamics of unstable detonation limits. Finally, the meso-scale experiments and simulations will permit the development and calibration of macro-scopic models at engineering scales for the appropriate global reaction rate in detonation waves. The outcome of the proposed research program is two-fold. Firstly, the development of a predictive capability of detonation related problems at the macro-scale engineering level through a bottom-up approach will find use in the prediction of such phenomena in the propulsion technology development and petro-chemical safety assessments. Secondly, and most importantly, it will provide training to students with the state-of-the-art solution methodologies in the field.