Amplification of thermoacoustic flame response to investigate high frequency combustion instabilities with LES

IF 6.2 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame Pub Date : 2025-07-31 DOI:10.1016/j.combustflame.2025.114317

Jonas Eigemann , Philip Bonnaire , Lukasz Panek , Christian Beck , Wolfgang Polifke , Andreas Kempf

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引用次数: 0

Abstract

We present a novel technique to enhance the thermoacoustic coupling in large-eddy simulations (LES) of self-excited oscillations, aiming to (a) recover high frequency thermoacoustic oscillations lost to the effect of LES-filtering, and to (b) establish a measure for a flame‘s proximity to the thermoacoustic stability limit. To this end, the naturally occurring link between isentropic pressure fluctuations and heat release rate is amplified. This thermoacoustic flame response amplification (TAFRA) is demonstrated in a compressible reactive LES of a single-jet case with experimentally confirmed high frequency thermoacoustic instability. TAFRA was found to not alter (non-acoustic) flame-properties and to selectively target thermoacoustic modes only, without amplifying the hydrodynamic instability modes. TAFRA has the potential of reducing the computational cost for the LES of high-frequency thermoacoustics, where acoustic resolution is the limiting factor, enabling more affordable simulations and design variations.

Novelty and Significance

In this paper, we present a novel method and a prototype implementation to artificially amplify the response of a flame to acoustic waves by increasing sensitivity to isentropic pressure fluctuations. The method contributes to the investigation of high-frequency thermoacoustic instabilities with large-eddy simulations (LES). The method amplifies the energy transferred from the flame to the acoustic field, which enables the prediction of high-frequency thermoacoustic instabilities with an LES grid that is sufficient for the flame, but not much finer, and therefore significantly lowers computational cost. At the same time, the paper demonstrates the important effect of pressure fluctuations on flame speed and thus on thermoacoustics. The new method may, eventually, also enable the quantification of thermoacoustic stability, i.e. the proximity to stability or instability.

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用LES放大热声火焰响应研究高频燃烧不稳定性

我们提出了一种新的技术来增强自激振荡大涡模拟（LES）中的热声耦合，旨在(a)恢复因LES滤波影响而丢失的高频热声振荡，以及(b)建立火焰接近热声稳定性极限的测量。为此目的，等熵压力波动和热释放率之间自然存在的联系被放大了。这种热声火焰响应放大（TAFRA）在单射流的可压缩反应性LES中得到了证明，实验证实了高频热声不稳定性。TAFRA被发现不会改变（非声学）火焰特性，并且只选择性地针对热声模式，而不会放大水动力不稳定模式。TAFRA有可能降低高频热声学LES的计算成本，其中声学分辨率是限制因素，从而实现更实惠的模拟和设计变化。在本文中，我们提出了一种新的方法和原型实现，通过增加对等熵压力波动的敏感性来人为地放大火焰对声波的响应。该方法有助于用大涡模拟（LES）研究高频热声不稳定性。该方法放大了从火焰传递到声场的能量，这使得能够使用足以用于火焰的LES网格预测高频热声不稳定性，但没有更精细，因此大大降低了计算成本。同时，本文还论证了压力波动对火焰速度和热声学的重要影响。这种新方法最终也可以量化热声稳定性，即接近稳定性或不稳定性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Combustion and Flame 工程技术-工程：化工

CiteScore

9.50

自引率

20.50%

发文量

631

审稿时长

3.8 months

期刊介绍： The mission of the journal is to publish high quality work from experimental, theoretical, and computational investigations on the fundamentals of combustion phenomena and closely allied matters. While submissions in all pertinent areas are welcomed, past and recent focus of the journal has been on: Development and validation of reaction kinetics, reduction of reaction mechanisms and modeling of combustion systems, including: Conventional, alternative and surrogate fuels; Pollutants; Particulate and aerosol formation and abatement; Heterogeneous processes. Experimental, theoretical, and computational studies of laminar and turbulent combustion phenomena, including: Premixed and non-premixed flames; Ignition and extinction phenomena; Flame propagation; Flame structure; Instabilities and swirl; Flame spread; Multi-phase reactants. Advances in diagnostic and computational methods in combustion, including: Measurement and simulation of scalar and vector properties; Novel techniques; State-of-the art applications. Fundamental investigations of combustion technologies and systems, including: Internal combustion engines; Gas turbines; Small- and large-scale stationary combustion and power generation; Catalytic combustion; Combustion synthesis; Combustion under extreme conditions; New concepts.