UNS: Collaborative Research: Experiments and Theory of Nonequilibrium Processes in Turbulent Combustion

1511834（拉曼，安阿伯大学）/1511025（克莱门斯，得克萨斯大学奥斯汀分校）由于燃料燃烧，在发动机和发电厂的条件下，流体流动是复杂的。 该研究小组建议通过使用先进的计算机模拟技术，并借助先进的激光测量来研究流体流动现象。 结果将用于构建模型的火焰和流动预测在这种复杂的条件下。研究生和本科生都将参与这项研究。提出了一种新的多尺度模拟方法，用于研究低马赫数、高湍流度的预混和非预混喷射反应流中尺度间的能量传递机制。 对于实验工作，先进的，基于激光的诊断工具，提出了：PIV（粒子成像测速）和瑞利和拉曼散射的速度场和标量/物种浓度测量，分别。 实验数据将提供大量统计数据，这些数据与速度场和标量场中非平衡的存在和影响有直接关系。 它们还将用于与基于DNS（直接数值模拟）的CFD（计算流体动力学）模拟结果进行比较，以了解燃烧和湍流之间的相互作用以及湍流燃烧中各种长度尺度下发生的现象之间的相互作用。 此外，通过使用时间和长度尺度表征非平衡产生的脉冲，湍流火焰的结构和演变进行了研究。 变分多尺度方法将被用作非平衡湍流燃烧建模的框架，其中跨脉冲生成尺度的能量传递将被明确建模。 将开发一个基于小参数展开的非定常耗散率模型。这些实验对于建模工作至关重要，因为可以研究的条件范围比DNS可能的条件范围大得多。

1511834 (Raman, University of Michigan-Ann Arbor)/1511025 (Clemens, University of Texas-Austin)Fluid flows are complicated under conditions found in engines and power plants, due to fuel combustion. The research team proposes to investigate the fluid flow phenomenon by using the state-of-art computer simulation techniques with the help of advanced laser-based measurements. The results will be used for constructing models for the flame and flow predictions under such complex conditions. Both graduate and undergraduate students will be involved in the research. The PIs also propose K-12 activities.A novel multi-scale modeling approach is proposed to elucidate energy transfer mechanisms between scales in low-Mach number and highly turbulent reacting flows with premixed and non-premixed injections. For the experimental effort, advanced, laser-based diagnostic tools are proposed: PIV (particle imaging velocimetry) and Rayleigh and Raman scattering for velocity field and scalar/species concentration measurements, respectively. The experimental data will provide large ensembles of statistical data that have direct bearing on the presence and impact of non-equilibrium in the velocity and scalar fields. They will also be used for comparison with result from CFD (Computational Fluid Dynamics) simulation, based on DNS (Direct Numerical Simulation), to understand the interaction between combustion and turbulence and between phenomena occurring at various length scales in turbulent combustion. Furthermore, by using time and length scales characterizing non-equilibrium generating impulses, the structure and evolution of turbulent flames will be studied. A variational multiscale approach will be used as a framework for modeling non-equilibrium turbulent combustion, where the energy transfer across impulse-generating scales will be modeled explicitly. A small-parameter expansion based unsteady dissipation rate model will be developed. The experiments will be critical to the modeling effort since a far larger range of conditions can be investigated than is possible with DNS.