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

1511834 (Raman, University of Michigan-Ann Arbor)/1511025 （Clemens, University of Texas-Austin）在发动机和发电厂中，由于燃料燃烧，流体流动是复杂的。研究小组建议利用最先进的计算机模拟技术和先进的激光测量技术来研究流体流动现象。研究结果将用于构建在这种复杂条件下火焰和流动预测的模型。研究生和本科生都将参与研究。pi还提议K-12活动。提出了一种新的多尺度建模方法来阐明低马赫数和高湍流反应流中预混和非预混注入的能量传递机理。对于实验工作，提出了先进的基于激光的诊断工具：PIV（粒子成像速度测量）和瑞利和拉曼散射分别用于速度场和标量/物质浓度测量。实验数据将提供大量的统计数据，这些数据对速度场和标量场中非平衡态的存在和影响有直接的影响。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，以了解燃烧与湍流之间的相互作用以及湍流燃烧中不同长度尺度上发生的现象之间的相互作用。此外，利用表征非平衡产生脉冲的时间和长度尺度，将研究湍流火焰的结构和演化。变分多尺度方法将被用作非平衡湍流燃烧建模的框架，其中跨脉冲产生尺度的能量传递将被明确地建模。建立了基于小参数膨胀的非定常耗散率模型。实验对建模工作至关重要，因为可以研究的条件范围比DNS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.