Evaporation rates of droplet arrays in turbulent reacting flows
Evaporation rates of droplet arrays in turbulent reacting flows
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DOI：
10.1016/j.proci.2010.05.081
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
M. R. G. Zoby;S. Navarro-Martinez;A. Kronenburg;A. Marquis
中科院分区：
文献类型：
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作者：
M. R. G. Zoby;S. Navarro-Martinez;A. Kronenburg;A. Marquis
对规则有序液滴阵列的研究有助于分析局部对蒸发速率的影响。本文采用直接数值模拟方法，研究了惰性和反应性对流环境中，液滴密度和流动条件对煤油液滴蒸发的影响。采用了质量守恒水平集方法和Ghost流体方法相结合的新模型。将数值模拟结果与RANS方法和大涡模拟(LES)中常用的两种蒸发模型进行了比较。结果表明，使用这些模型预测稠密喷雾的蒸发速率只取得了有限的成功。在所研究的大多数情况下，使用1/3规则来计算混合物性质会导致对蒸发率的低估约20%到50%。如果蒸发速率模型中的性质是基于液滴周围的近场性质，则该模型只能准确地预测结果，误差小于2%。对湍流对蒸发过程影响的进一步研究表明，蒸发速率与亚格子动能之间没有明显的相关性，这与湍流对水滴表面扩散的影响有关。
Studies of regularly ordered droplet arrays facilitate the analysis of local effects on evaporation rates. This work investigates, using Direct Numerical Simulations (DNS), the effects of droplet density and flow conditions on evaporation of kerosene droplets in inert and reactive convective environments. A novel model, coupling a mass conservative Level Set approach with the Ghost Fluid method, is used. The rates obtained from the DNS are compared to two evaporation models based on heat and mass transfer numbers commonly used for RANS methods and Large Eddy Simulations (LES). The results show that predictions of evaporation rates of dense sprays using these models has a limited success. The use of the 1/3-rule to calculate mixture properties results in underpredictions of the evaporation rates by around 20% to 50% in most of the cases studied. The models can only predict the DNS results accurately with errors lower than 2%, if the properties in the evaporation rate models are based on properties in the near field around the droplet. Further studies on the effects of turbulence on the evaporation process showed no evident correlation between the evaporation rates and the subgrid kinetic energy relating the effects of turbulence to vapour dispersion away from the droplet surface.