Dynamics of Swirl and Jet Flames (SWJET)

热声燃烧不稳定性的预测与控制对高效精益预混燃烧系统的开发提出了严峻的挑战。当前TCI模型的一个关键输入是火焰传递函数（FTF），它表示火焰对声强迫的响应。目前，它是从广泛的测量、高保真的数值模拟或高度简化的分析模型中推断出来的。在SWJET项目中，我们建议开发一种整体方法，从相关的控制方程中确定FTF和相关的流动和火焰动力学，这些方程围绕基本状态线性化，即无扰动湍流火焰的流动变量的时间平均分布。这种线性化反应流（LRF）方法最近由Avdonin等人，Proc. Comb进行了探索。本月,2019。虽然取得了令人满意的结果，但研究仅限于基于一步化学的层流火焰。SWJET项目的中心目标是将LRF求解器的应用范围扩展到更复杂的反应机制和湍流火焰。SWJET项目分为三个工作区域（WA）。WA 1将专注于层流火焰。更先进的化学模型将被整合到线性化的求解器中。在线性框架下得到的火焰动力学将通过强迫和自激火焰的非线性数值模拟进行验证。wa2是本项目的核心，将探索线性化方法对湍流反应流的适用性，并通过湍流射流火焰的LES验证结果。线性方法将应用于预测声谐波强迫下的流动和火焰响应，并提高对相关物理机制的理解。在wa3中，重复了wa2中紊流漩涡火焰的工作流程。特别关注的将是涡流波的产生和传输，以及它们对火焰动力学的影响。两个研究小组都对火焰动力学的分析和建模做出了重大贡献。特别是，在TUB的专业知识是在描述高湍流反应流的流动动力学。相比之下，TUM的团队在线性化框架中处理反应层流方面获得了重要的互补经验。两个研究所的线性化求解器将在项目的早期阶段合并。由于它们的互补专业，这将推动本提案中列出的研究。SWJET将要开发的方法是燃烧科学的一次飞跃，因为它们开辟了分析和控制火焰动力学的新方法，特别是tci。SWJET项目将由FVV共同出资，费率为24%，其中包括第三次WA的个人费用。该项目进一步受益于另一个实验FVV项目，该项目为湍流射流和漩涡火焰的模型验证提供了经验数据。

The prediction and control of thermoacoustic combustion instabilities (TCIs) poses severe challenges to the development of efficient lean premixed combustion systems. A crucial input for current TCI models is the flame transfer function (FTF), which represents the response of the flame to acoustic forcing. It is currently deduced from extensive measurements, high-fidelity numerical simulations, or strongly simplified analytic models. In the SWJET project we propose to develop a holistic method to determine the FTF and the related flow and flame dynamics from the pertinent governing equations linearized around a base state, i.e. time-averaged distributions of flow variables of the unperturbed turbulent flame. This Linearized Reactive Flow (LRF) approach was recently explored by Avdonin et al., Proc. Comb. Inst. 2019. Promising result were obtained, but the study was limited to a laminar flame based on one-step chemistry. The central goal of the SWJET project is to extend the application range of LRF solvers to more complex reaction mechanisms and turbulent flames. The SWJET project is structured in three Work Areas (WA). WA 1 will focus on laminar flames. More advanced chemistry models will be integrated in the linearized solver. Flame dynamics obtained in the linear framework will be validated against nonlinear numerical simulations of forced and self-excited flames. WA 2, which constitutes the core of this project, will explore the applicability of the linearized methods to turbulent reacting flows and validate results against LES of a turbulent jet flame. The linear methods will be applied to predict the flow and flame response to acoustic harmonic forcing and to improve the understanding of the relevant physical mechanisms. In WA 3, the workflow of WA 2 is repeated for a turbulent swirl flame. Special focus will be on the generation and transportation of swirl waves, as well as their impact on flame dynamics. Both research groups contributed significantly to the state-of-the-art of analysis and modeling of flame dynamics. In particular, the expertise at TUB is on describing flow dynamics in highly turbulent reacting flows. The group at TUM, in contrast, has acquired significant complementary experience in treating reacting laminar flows in a linearized framework. The linearized solvers from both institutes will be merged in an early stage of the project. Due to their complementary specialties this will propel the research lined out in this proposal. The methods that are to be developed in SWJET constitute a leap forward in combustion science, as they open up new ways to analyze and control flame dynamics in general and TCIs in particular. The SWJET project will be co-funded by the FVV at a rate of 24%, which covers the personal costs of the third WA. The projects further benefits from another, experimental FVV project at TUB, providing empirical data for model validation of the turbulent jet and swirl flames.