Abstract Spray reactive flow finds application in various technical devices, and due to the complex nature, their optimization is very challenging, requiring proper modeling of turbulence/chemistry interactions as well as of the contribution from spray evaporation. This work presents a study of sub-grid scale combustion models, where relevant assumptions on multiphase coupling and their effects are analyzed in detail. For this purpose, two different flamelet approaches, i.e. progress variable spray flamelet and multi-regime gas flamelet are examined in an implementation coupled with the dynamic thickened flame model, along with which the impact of inlet inhomogeneities condition and droplet evaporation taking into account internal temperature gradient is also investigated. The numerical evaluation is carried out in large eddy simulations of a benchmark ethanol spray flame with partial pre-vaporization, where an Eulerian-Lagrangian numerical framework is adopted. The analysis demonstrated that the flame dynamics under consideration is governed by a close coupling between spray evaporation, turbulent dispersion and unsteady flame propagation at upstream shear layers. Results show that the spray flamelets built from counterflow partially-premixed spray flames achieved a better agreement with experiments, capturing the flame structure in terms of gas-phase temperature, OH mass fraction as well as spray statistics.

中文翻译：

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使用多相 DTF/flamelet 模型对部分预汽化乙醇反应喷雾进行大涡模拟

摘要 喷雾反应流在各种技术设备中得到应用，由于其复杂性，它们的优化非常具有挑战性，需要对湍流/化学相互作用以及喷雾蒸发的贡献进行适当的建模。这项工作提出了亚电网尺度燃烧模型的研究，其中详细分析了多相耦合的相关假设及其影响。为此，在结合动态增厚火焰模型的实施中检查了两种不同的小火焰方法，即进度可变喷射小火焰和多机制气体小火焰，同时考虑了内部温度的入口不均匀条件和液滴蒸发的影响还研究了梯度。数值评估是在具有部分预汽化的基准乙醇喷雾火焰的大涡模拟中进行的，其中采用了欧拉-拉格朗日数值框架。分析表明，所考虑的火焰动力学受喷雾蒸发、湍流扩散和上游剪切层不稳定火焰传播之间的密切耦合控制。结果表明，由逆流部分预混喷射火焰构建的喷射火焰与实验更加吻合，在气相温度、OH 质量分数和喷射统计方面捕获了火焰结构。分析表明，所考虑的火焰动力学受喷雾蒸发、湍流扩散和上游剪切层不稳定火焰传播之间的密切耦合控制。结果表明，由逆流部分预混喷射火焰构建的喷射火焰与实验更加吻合，在气相温度、OH 质量分数和喷射统计方面捕获了火焰结构。分析表明，所考虑的火焰动力学受喷雾蒸发、湍流扩散和上游剪切层不稳定火焰传播之间的密切耦合控制。结果表明，由逆流部分预混喷射火焰构建的喷射火焰与实验更加吻合，在气相温度、OH 质量分数和喷射统计方面捕获了火焰结构。