Multiscale Turbulent Reacting Flows and Data-Based Modeling

本研究项目研究了一种用于湍流火焰计算的多尺度火焰嵌入方法。该模型基于描述流动的大涡模拟(LES)和火焰跟踪的耦合，以及基于一维湍流(ODT)模型的嵌入的一维随机解。该框架的重要功能包括将ODT解决方案提升到LES，将LES解决方案降低到ODT，以及捕获火焰锋面。拉格朗日LES-ODT公式要求在ODT溶液沿火焰平流时跟踪、产生和去除ODT溶液。该公式还需要一个稳健的公式，用于过滤从ODT的细粒溶液到LES的密度，以及过滤用于跟踪LES中火焰的标量的输运和源项。将研究基于小波的方法，以建立LES和ODT速度场及其传输之间的一致性。为了提高计算效率，将使用主成分分析对热化学标量进行优化参数化。这项研究致力于通过燃烧产生能量的物理过程的预测。这项工作旨在开发下一代建模工具，通过模拟潜在地减少燃烧系统设计的周转时间，并研究提高燃烧效率和减少污染物的机理。

This research project investigates a multiscale flame-embedding approach for the computation of turbulent flames. The model is based on the coupling of large-eddy simulation (LES) for the description of the flow and for flame tracking and embedded 1D stochastic solutions of flamelets based on the one-dimensional turbulence (ODT) model. Important features of the framework include the upscaling of ODT solution to the LES, the downscaling of LES solutions to ODT, and capturing of the flame front. The Lagrangian LES-ODT formulation requires the tracking, spawning, and removal of ODT solutions as they are advected along the flame. The formulation also requires a robust formulation for the filtering of the density from the fine-grained solution of ODT to the LES along with the filtering of transport and source terms for scalars used to track the flame in LES. Wavelet-based methods will be investigated to establish consistency between the LES and ODT velocity fields and their transport. An optimal parameterization of the thermo-chemical scalars using principal component analysis will be used to improve computational efficiency. This research addresses the prediction of physical processes occurring in the production of energy through combustion. The work aims to develop next-generation modeling tools that can potentially reduce the turn-around time for the design of combustion systems through simulation and to investigate mechanisms to improve combustion efficiency and reduce pollutants.