One-dimensional flame subject to periodic and sinusoidal motion: frequency domain analysis and flame-motion contribution to combustion instability

IF 5.8 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame Pub Date : 2025-06-21 DOI:10.1016/j.combustflame.2025.114285

Aurelien Genot , Stéphane Boulal , Jean-Michel Klein , Axel Vincent-Randonnier , Arnaud Mura

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引用次数: 0

Abstract

Combustion instabilities are often an outcome of the interaction between fluctuations in the flame-induced heat release rate (HRR) and acoustic modes of the combustor. Thus, they are a direct consequence of the flame unsteady dynamics, which itself features multiple contributions. The present study is focused on one of them, namely that of the flame motion. Two distinct spatial distributions of the HRR subject to a periodic and sinusoidal motion (slower than the speed of sound) are analyzed in terms of its normalized motion amplitude. For these two distributions, a frequency domain analysis is conducted and the presence of peaks at the motion frequency, together with higher harmonics, are put into evidence. Thus, it is established that, even in (i) a simplified one-dimensional situation and (ii) with a slow periodic and sinusoidal motion featuring moderate amplitudes, flame motions can drive an energy transfer from the fundamental frequency to upper harmonics. This serves as a basis for the development of a simplified model, which is found able to retrieve the corresponding response in terms of its fundamental and harmonic frequencies. Flame-flow couplings are subsequently analyzed on the basis of stability criteria based on the Rayleigh index, the Chu index and a nonlinear index. This leads to the identification of a threshold value of the normalized motion amplitude with the flame motion contribution acting either as a source term below this value or as a damping term once it is exceeded.

Novelty and significance

This manuscript is focused on the flame motion contribution to flame dynamics and brings some new insights to the current state of the art: (i) for a periodic and sinusoidal motion, the flame response displays several harmonics that are triggered regardless of the motion amplitude and HRR distribution, (ii) a nonlinear and multi-harmonic model of the HRR fluctuations is presented for a boxcar HRR distribution moving periodically, and (iii) a threshold amplitude of the order of twenty times the flame thickness defines the flame motion contribution to combustion instabilities.

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周期性和正弦运动的一维火焰：频域分析和火焰运动对燃烧不稳定性的贡献

燃烧不稳定性通常是火焰引起的热释放率（HRR）波动与燃烧器的声模态之间相互作用的结果。因此，它们是火焰非定常动力学的直接结果，它本身具有多重贡献。本文的研究重点是其中的一种，即火焰运动。根据归一化运动幅度，分析了周期运动和正弦运动（慢于声速）下HRR的两种不同空间分布。对这两种分布进行了频域分析，发现在运动频率处存在峰值和高次谐波。因此，可以确定，即使在(i)简化的一维情况下和（ii）缓慢的周期和正弦运动且振幅适中的情况下，火焰运动也可以驱动能量从基频到上谐波的传递。这可以作为开发简化模型的基础，发现该模型能够根据其基频和谐波频率检索相应的响应。基于Rayleigh指数、Chu指数和非线性指数的稳定性准则对火焰流耦合进行了分析。这导致确定归一化运动幅度的阈值，火焰运动贡献要么作为低于该值的源项，要么作为超过该值的阻尼项。新颖性和意义：该手稿集中在火焰运动对火焰动力学的贡献，并为当前的艺术状态带来了一些新的见解：(i)对于周期性和正弦运动，无论运动幅度和HRR分布如何，火焰响应都显示出触发的几个谐波；（ii）对于周期性运动的箱车HRR分布，提出了HRR波动的非线性和多谐波模型；（iii）火焰厚度20倍的阈值幅度定义了火焰运动对燃烧不稳定性的贡献。

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.