The aim of this study is to investigate single ethanol droplet evaporation characteristics under premixed CH4/air flame conditions via experimental and numerical approaches. In the experimental part of the study, ethanol droplet with an initial diameter between 20 and 70 µm was injected through a flat laminar stagnant flame. Visualization of the flame front and temporal monitoring of the droplet evaporation at high temperatures up to 2200 K were performed using planar laser tomography. Droplet motion and its diameter change are captured simultaneously via PIV/PTV and ILIDS diagnostics, respectively. Velocity measurements indicated that the droplets are small enough to be carried by surrounding gas with a very small slip velocity. Variation in droplet diameter is successfully tracked through the flame via ILIDS and it is found to be more drastic in burnt gases. Hence, vaporization rates are reported at burnt gas temperature which is affected by the heat losses from flame to the stagnation plate due to the change in the temperature profile. In the numerical part of the study, single droplet evaporation under constant temperature and stagnant environment was studied with Spalding model using YALES2 solver. The variations of the droplet properties were computed under N2 atmosphere and under flame conditions. At elevated conditions, flame temperature is found to have a more dominant effect on the evaporation rate rather than the burnt gas composition.

中文翻译：

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火焰条件下分离的乙醇液滴的汽化特性

本研究的目的是通过实验和数值方法研究预混合 CH4/空气火焰条件下的单个乙醇液滴蒸发特性。在研究的实验部分，初始直径在 20 到 70 µm 之间的乙醇液滴通过扁平层流停滞火焰注入。使用平面激光断层扫描在高达 2200 K 的高温下进行火焰前沿的可视化和液滴蒸发的时间监测。分别通过 PIV/PTV 和 ILIDS 诊断同时捕获液滴运动及其直径变化。速度测量表明液滴足够小，可以被周围气体以非常小的滑移速度携带。通过 ILIDS 成功跟踪了液滴直径的变化，发现在燃烧气体中变化更为剧烈。因此，汽化率是在燃烧气体温度下报告的，该温度受到由于温度分布变化而从火焰到停滞板的热量损失的影响。在研究的数值部分，采用 YALES2 求解器，采用 Spalding 模型研究了恒温和停滞环境下的单液滴蒸发。在 N2 气氛和火焰条件下计算液滴特性的变化。在升高的条件下，发现火焰温度对蒸发速率的影响比燃烧气体成分的影响更大。汽化率是在燃烧气体温度下报告的，该温度受到由于温度分布变化而从火焰到停滞板的热量损失的影响。在研究的数值部分，采用 YALES2 求解器，采用 Spalding 模型研究了恒温和停滞环境下的单液滴蒸发。在 N2 气氛和火焰条件下计算液滴特性的变化。在升高的条件下，发现火焰温度对蒸发速率的影响比燃烧气体成分的影响更大。汽化率是在燃烧气体温度下报告的，该温度受到由于温度分布变化而从火焰到停滞板的热量损失的影响。在研究的数值部分，采用 YALES2 求解器，采用 Spalding 模型研究了恒温和停滞环境下的单液滴蒸发。在 N2 气氛和火焰条件下计算液滴特性的变化。在升高的条件下，发现火焰温度对蒸发速率的影响比燃烧气体成分的影响更大。在 N2 气氛和火焰条件下计算液滴特性的变化。在升高的条件下，发现火焰温度对蒸发速率的影响比燃烧气体成分的影响更大。在 N2 气氛和火焰条件下计算液滴特性的变化。在升高的条件下，发现火焰温度对蒸发速率的影响比燃烧气体成分的影响更大。