A single ethanol droplet evaporation through laminar methane/air stagnation flame is investigated at lean, stoichiometric and rich conditions experimentally and numerically. For the droplets having initial diameters of 20-, the particle Reynolds number is measured via PIV/PTV, resulting in the slip velocity between the droplet and gas flow being small and the surrounding gas being able to carry without any significant convective effects. Evaporation rates, computed from Abramzon–Sirignano for a moving droplet towards a stagnation flame field, satisfy the ones computed from empirically determined evaporation rates from ILIDS measurements as a function of flame temperature, flame speed and flame thickness. Nevertheless, Abramzon–Sirignano model slightly overestimates the vaporization constant for lean cases. The distance traveled by the droplet after leaving the flame zone determines the average critical diameter. Accordingly, droplets larger than can cross the flame, leading to local modifications in the flame region due to heat loss and vapor diffusion from the droplet. Energy conversion in combustion should be carried out by optimizing efficiency, minimizing pollution, and preventing further climate change. The multiphase nature of spray combustion particularly adds further complexity due to the strong coupling of atomization, evaporation, mixing, turbulence, and chemical reactions. Although spray combustion involves a cloud of polydispersed droplets, it is of fundamental importance to understand the dynamics of an isolated droplet and its interactions with the flame front, which can provide indispensable information for spray combustion models. In this study, an experimental and computational framework has been developed to investigate droplet-flame interactions. The dynamics and evaporation characteristics of an isolated droplets interacting with stagnation flames have been determined by coupling several laser diagnostics, while further enhanced with Eulerian–Lagrangian simulations under flame conditions. Thereupon, the outcomes help the design of injectors of spray combustion systems and enhancement of evaporation models.

中文翻译：

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火焰特性对通过停滞甲烷/空气火焰蒸发的孤立乙醇液滴的影响：实验和数值研究

通过实验和数值研究了在贫油、化学计量和富油条件下通过层流甲烷/空气停滞火焰的单乙醇液滴蒸发。对于初始直径为20的液滴，通过PIV/PTV测量颗粒雷诺数，导致液滴与气流之间的滑移速度很小，并且周围气体能够携带而没有任何明显的对流效应。对于向静止火焰场移动的液滴，根据 Abramzon-Sirignano 计算得到的蒸发率满足根据 ILIDS 测量经验确定的蒸发率计算得出的蒸发率，作为火焰温度、火焰速度和火焰厚度的函数。然而，Abramzon-Sirignano 模型稍微高估了稀情况下的汽化常数。离开火焰区后液滴所行进的距离决定了平均临界直径。因此，大于可以穿过火焰的液滴，由于热量损失和液滴的蒸汽扩散而导致火焰区域的局部改变。燃烧中的能量转换应通过优化效率、最大限度地减少污染和防止进一步的气候变化来进行。由于雾化、蒸发、混合、湍流和化学反应的强烈耦合，喷雾燃烧的多相性质特别增加了复杂性。尽管喷雾燃烧涉及多分散液滴云，但了解孤立液滴的动力学及其与火焰锋的相互作用至关重要，这可以为喷雾燃烧模型提供不可或缺的信息。在这项研究中，开发了一个实验和计算框架来研究液滴-火焰相互作用。与停滞火焰相互作用的孤立液滴的动力学和蒸发特性已通过耦合几种激光诊断来确定，同时通过火焰条件下的欧拉-拉格朗日模拟进一步增强。因此，研究结果有助于喷雾燃烧系统喷射器的设计和蒸发模型的增强。