Abstract The vaporization rate of reacting aluminum droplets in high-speed flows plays a crucial role in determining the energy released during the combustion of aluminized solid propellants and explosives. This work develops a model for the vaporization rate of burning aluminum droplets in shocked flows using data from high-resolution simulations. A levelset-based sharp-interface method is used to resolve the dynamics at the droplet-air interface. Several reactive calculations of shock-droplet interaction are performed in the parameter space of Mach number (1.1 - 3.5) and Reynolds number (100 – 1000) to understand the influence of local flow parameters on the flame structure around the reacting aluminum droplet. The results show a transition from diffusion limited to kinetically limited combustion of the aluminum droplets when the Mach number is increased and the droplet size or the Reynolds number is decreased. The transition from diffusion-limited combustion to kinetically limited combustion is found to significantly affect the flame dynamics and vaporization rate of the reacting droplets. Therefore, empirical models for the vaporization rate of droplets, developed for diffusion limited combustion regimes, do not represent the kinetically limited combustion in high Mach number conditions. A new model for the Sherwood number spanning diffusion and kinetically limited regimes of the reacting aluminum droplets is developed using an economical multi-fidelity surrogate modeling technique. The current model for the Sherwood number for reacting aluminum droplets will be useful in predicting the energy released from the combustion of aluminized energetic materials in shocked flows. Although the current method is developed in the context of aluminum droplet combustion, it can be extended to develop surrogate models of Sherwood number for general liquid fuel droplets in compressible flows.

中文翻译：

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冲击流中反应铝液滴蒸发率的锐界面计算

摘要 高速流动中反应铝液滴的汽化速率在决定铝化固体推进剂和炸药燃烧过程中释放的能量方面起着至关重要的作用。这项工作使用高分辨率模拟的数据开发了冲击流中燃烧铝液滴的蒸发率模型。基于水平集的锐界面方法用于解决液滴-空气界面的动力学问题。在马赫数 (1.1 - 3.5) 和雷诺数 (100 - 1000) 的参数空间中进行了多次冲击-液滴相互作用的反应计算，以了解局部流动参数对反应铝液滴周围火焰结构的影响。结果表明，当马赫数增加并且液滴尺寸或雷诺数降低时，铝液滴从扩散受限到动力学受限燃烧的转变。发现从扩散限制燃烧到动力学限制燃烧的转变显着影响反应液滴的火焰动力学和汽化速率。因此，为扩散受限燃烧机制开发的液滴蒸发率经验模型并不代表高马赫数条件下的动力学受限燃烧。使用经济的多保真代理建模技术开发了一种新的舍伍德数跨越扩散和反应铝液滴动力学限制机制的模型。用于反应铝液滴的舍伍德数的当前模型将有助于预测冲击流中镀铝高能材料燃烧释放的能量。虽然目前的方法是在铝液滴燃烧的背景下开发的，但它可以扩展到开发可压缩流中一般液体燃料液滴的舍伍德数的替代模型。