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Interactions between Multiple Unstable Transversal Modes in High-Frequency Thermoacoustic Systems

高频热声系统中多种不稳定横向模式之间的相互作用

基本信息

批准号：
380974143
负责人：
Professor Dr.-Ing. Thomas Sattelmayer
金额：
--
依托单位：
Lehrstuhl für Thermodynamik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/380974143?language=en
关键词：
Interactions between Multiple Unstable Transversal

项目摘要

In the past, linear and nonlinear dynamics related to non-compact, multi-dimensional, high-frequency thermoacoustic oscillations in air-breathing, premixed combustion systems have been investigated with a single mode assumption. This implies the existence of only one linearly unstable acoustic mode that governs the limit-cycle oscillations, while further modes are presumed as linearly stable and of negligible relevance. However, this single mode notion is questionable especially in the high-frequency regime beyond the concerned combustion chamber's cut-on frequency, where multiple linearly unstable modes exist and interact. A non-consideration of all possibly unstable modes would compromise a stable and reliable combustor operation. For the first time, the proposed project seeks to establish a fundamental understanding on physical mechanisms that govern high-frequency thermoacoustic oscillations constituted by multiple unstable modes. For this purpose, a lab-scale, swirl-stabilized, premixed combustor in which multiple transversal modes in the high-frequency regime are linearly unstable serves as a benchmark system. Specifically, the proposed project is divided into three main research objectives: The first one aims to unravel linear flame driving mechanisms and nonlinear combustor dynamics of the second transversal mode. This includes, besides understanding of principal physics, the development of appropriate mathematical quantification and simulation tools. Specific knowledge on interaction mechanisms between multiple unstable transversal modes in terms of physical explanations and modeling approaches shall be generated through the second objective. Finally, the third objective seeks to develop and validate reliable system identification methodologies to extract relevant thermoacoustic parameters (e.g. linear growth rates) that are particularly applicable to multi-modal systems.

在过去，线性和非线性动力学相关的非紧凑，多维，高频热声振荡的空气呼吸，预混燃烧系统已被研究与一个单一的模式假设。这意味着只存在一个线性不稳定的声学模式，控制极限环振荡，而其他模式被假定为线性稳定和可忽略的相关性。然而，这种单一模式的概念是值得怀疑的，特别是在高频制度以外的有关燃烧室的截止频率，其中存在多个线性不稳定的模式，并相互作用。如果不考虑所有可能的不稳定模态，就会损害燃烧室稳定可靠的工作。该项目首次试图建立对由多个不稳定模式构成的高频热声振荡的物理机制的基本理解。为此，实验室规模的，旋流稳定，预混燃烧室中的多个横向模式在高频区是线性不稳定的作为基准系统。具体而言，拟议的项目分为三个主要的研究目标：第一个旨在解开线性火焰驱动机制和非线性燃烧室动力学的第二横向模式。这包括，除了了解主要的物理，适当的数学量化和模拟工具的发展。通过第二个目标，将在物理解释和建模方法方面产生关于多个不稳定横向模式之间相互作用机制的具体知识。最后，第三个目标是开发和验证可靠的系统识别方法，以提取相关的热声参数（如线性增长率），特别适用于多模态系统。