Large Eddy Simulation of a supersonic lifted flame using the Eulerian stochastic fields method
Large Eddy Simulation of a supersonic lifted flame using the Eulerian stochastic fields method
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DOI：
10.1016/j.proci.2018.08.040
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发表时间：
2019
影响因子：
3.4
通讯作者：
Y. Almeida;S. Navarro-Martinez
中科院分区：
文献类型：
--
作者：
Y. Almeida;S. Navarro-Martinez
超燃冲压发动机推进系统可能是交付下一代高超声速飞机的关键。收集实验数据的高成本和复杂性是此类发动机开发的限制因素。在这种背景下，数值模拟已变得越来越流行，以研究超音速燃烧现象，否则将是令人望而却步的昂贵。尽管最近取得了进展，但高速可压缩和反应性流动的模拟仍然非常具有挑战性，并提出了许多相关的挑战。化学源项是高度非线性的，大多数燃烧模型被设计为在低马赫数条件下运行。本文研究了概率密度函数(PDF)在超音速大涡模拟模型中的应用。考虑了两种方法：一种是对高速流动的标量-能量联合PDF模型的推广，另一种是一种新的速度-标量-能量联合PDF模型。这两种公式都使用欧拉随机场方法，该方法在完全可压缩的基于密度的CFD程序中实现。在超音速升空火焰中对模型的性能进行了研究，并与忽略亚网格起伏的传统模型进行了比较。结果表明，在粗网格中，亚网格的贡献是重要的，而随机场方法可以再现实验数据和观测到的散射。模拟结果表明，标量焓PDF格式是最稳健的格式，而速度标量PDF格式的亚网格闭合问题还有待进一步研究。
Scramjet propulsion systems can be the key to deliver the next generation of hypersonic planes. The high costs and complexity of gathering experimental data is a limiting factor in the development of such engine. In this context, numerical simulation has become increasingly popular to investigate supersonic combustion phenomena that otherwise would be prohibitively expensive. Despite recent progress, the simulation of high-speed compressible and reactive flows is still very challenging and presents many associated challenges. The chemical source term is highly non-linear and most combustion models are designed to operate in low-Mach number conditions. The present work investigates the use of Probability Density Function (PDF) in the context of Large Eddy Simulation models under supersonic conditions. Two approaches are considered: an extension of the joint scalar-enthalpy PDF for high-speed flows and a novel joint velocity-scalar-energy PDF model. Both formulations use the Eulerian stochastic fields approach implemented in a fully compressible density-based CFD code. The performance of the models are investigated in a supersonic lifted flame, comparing the stochastic formulations with traditional models that neglect sub-grid fluctuations. The results show that sub-grid contributions are important at coarse meshes and the stochastic fields approach can reproduce the experimental data and the scatter observed. The simulations suggest that the scalar-enthalpy PDF is the most robust formulations and the sub-grid closures of the joint velocity-scalar PDF need further investigation.