UNS: Collaborative Research: Spectral Energy Transfer in Turbulent Flames: From its Characterization to Subgrid Scale Models

主要研究人员建议通过使用最先进的计算机模拟技术和先进的基于激光的测量，研究如何更好地模拟流体流动（典型的设备，如发动机和发电厂的燃烧室）。这项研究的潜在好处包括更好地理解和设计燃烧器，提高效率和降低污染物排放。研究生和本科生都将参与研究，为未来的研究人员和工程师做好准备。本提案侧重于热释放对小尺度湍流结构影响的基础研究，旨在为发展基于物理的湍流反应模型提供见解和机制，而不是基于临时假设。实验组件包括新的速度测量，采用类似于层析成像的方法，在真正的三维流动中，速度测量覆盖了场的深度，而不是传统的二维截面。本文还将对柯尔莫哥洛夫的紊流动能级联平衡假设是否成立，以及如果不成立，该假设应在多大程度上、以何种方式被释热反应修正等问题进行深入探讨。测量跨越比通常使用PIV解决更广泛的动态范围的尺度。所提出的直接数值模拟（DNS）和分析很好地集中在热释放对湍流能谱和不同尺度间能量传递的影响问题上。

1512214 / Egolfopoulos, Fokion N.1512771 / Blanquart, GuillaumeThe principal investigators propose to investigate how fluid flows (typical in devices such as combustor in engines and power plants) can be better modelled by using the state-of-art computer simulation techniques with the help of advanced laser-based measurements. The potential benefits of the study include better understanding and design of combustors and higher efficiency and lower pollutant emissions. Both graduate and undergraduate students will be involved in the research and be prepared as future researchers and engineers. This proposal focuses on fundamental investigation of the effects of heat release on small scale turbulent structure and aims to provide insight and mechanisms for developing physics-based turbulent reacting models, rather than based on ad-hoc assumptions. The experimental components include novel velocity measurements, adopting an approach similar to tomography in that the velocity measurements cover the depth of the field instead of the traditional two-dimensional section in truly three-dimensional flows. Some insight will also be shed on whether Kolmogorov's equilibrium assumption for turbulent kinetic energy cascade is valid and, if not, to what extent and in what manner the assumption should be modified by the heat-releasing reactions. The measurements span over a broader dynamic range of scales than is normally addressed using PIV. The proposed direct numerical simulations (DNS) and analysis are well focused on questions of the effects of heat release on turbulent energy spectra and energy transfer between different scales.