部分预混旋流燃烧入口激励下的熵波产生及耗散机制研究

doi:10.11949/0438-1157.20251170

摘要/Abstract

摘要：

为揭示部分预混旋流燃烧中熵波的产生及演化机理，本研究主要通过LES-FGM方法，以甲烷为燃料，系统研究了空气入口周期性激励下熵波的产生与耗散过程，重点考察了激励频率、激励幅值与当量比的影响作用。研究发现，熵波的产生及耗散主要取决于燃烧室上游流动过程，受到周期性涡脱落与破碎、壁面约束、内回流区结构及剪切流动的共同作用。60 Hz激励下，熵波可维持较高稳定性，燃烧室出口仍能观测到约1%的扰动；而在100 Hz激励下，熵波受剪切流和内回流区的分散作用显著，出口扰动幅值衰减至约0.5%，体现出明显的低通滤波特性。当激励幅值增大时，燃烧存在贫燃和富燃间的转换，熵波幅值呈现非线性响应，扰动幅值进一步衰减至0.25%。当量比对熵波演化具有显著影响，尤其是在低当量比下流场紊乱加剧，导致熵波幅值显著下降且波形失真。通过POD模态分析发现，熵波具有明显的非平面特征，尤其在高频或低当量比条件下形态更为分散，表明在熵噪声建模中需谨慎对待理想化的平面熵波假设。本研究揭示了熵波的演化机制及其与旋流场的耦合效应，为燃烧室熵噪声预测与稳定性设计提供重要依据。

关键词: LES-FGM, 部分预混燃烧, 入口激励, 熵波, 流动-火焰耦合作用

Abstract:

To reveal the generation and evolution mechanisms of entropy wave in partially premixed swirl combustion, this study employed the LES-FGM method with methane fuel to systematically investigate the generation and dissipation of entropy wave under periodic excitation at the air inlet, focusing on effects of excitation frequency, amplitude, and equivalence ratio. Results show that entropy wave dynamics depend primarily on upstream flow processes, influenced by periodic vortex shedding and breakup, wall confinement, inner recirculation zone structure, and shear flow. Under 60 Hz excitation, entropy wave remains relatively stable with an about 1% outlet perturbation; at 100 Hz, shear flow and recirculation disperse waves, reducing perturbation to about 0.5%, demonstrating low-pass filtering characteristics. Increasing excitation amplitude induces lean-rich combustion transitions, leading to nonlinear amplitude response and further attenuation to about 0.25%. Low equivalence ratio increases flow disorder, reducing wave amplitude and distorting waveform. POD analysis reveals non-planar entropy wave characteristics especially under high-frequency excitation or low equivalence ratios, highlighting limitations of the planar wave assumption in entropy noise modeling. This work elucidates entropy wave evolution and swirl flow coupling which can support entropy noise prediction and combustor stability design.

Key words: LES-FGM, partially premixed combustion, inlet excitation, entropy wave, flow-flame interaction

中图分类号:

V231.2

何甲文, 李祥晟, 张玮杰, 胡光亚, 王金华, 黄佐华. 部分预混旋流燃烧入口激励下的熵波产生及耗散机制研究[J]. 化工学报, DOI: 10.11949/0438-1157.20251170.

Jiawen HE, Xiangsheng LI, Weijie ZHANG, Guangya HU, Jinhua WANG, Zuohua HUANG. Study on entropy wave production and dissipation in partially premixed swirl flames subject to inlet perturbations[J]. CIESC Journal, DOI: 10.11949/0438-1157.20251170.

图/表 10

图 1 部分预混旋流燃烧器示意图

Fig. 1 Schematic of the partial premixed swirl combustor

图 2 计算域和网格

Fig. 2 Computational domain and grid

表1 研究工况

Table 1 Operation conditions

工况	Φ	Q_CH4	Q_Air1	Q_Air2
Φ0.8_f100_A20	0.8	29.27	278.80	69.70
Φ0.8_f60_A20	0.8	29.27	278.80	69.70
Φ0.8_f100_A40	0.8	29.27	209.10	139.40
Φ0.6_f100_A20	0.6	22.39	284.30	71.08

图 3 不同轴向位置的平均速度

Fig. 3 Averaged velocity at different axial positions

图 4 无量纲温度信号及温度信号的FFT变换

Fig. 4 Non-dimensional temperature signal and FFT transformation of temperature signal

图 5 耗散指数受频率、幅值和当量比的影响规律

Fig. 5 The influence of frequency, amplitude, and equivalence ratio on the dissipation index

图 6 平面熵波演化过程注：图 6平面熵波演化过程

Fig. 6 Evolution process of entropy wave

图 7 燃烧室轴向不同位置热点分布

Fig. 7 Distribution of hot spots at different axial positions in the combustion chamber

图 8 主动激励下涡环的动态变化注：图 8主动激励下涡环的动态变化

Fig. 8 Dynamic changes of vortex rings under active excitation

图 9 温度波动POD分解前3阶模态注：图 9温度波动POD分解前3阶模态

Fig. 9 Temperature fluctuation： First three modes of POD decomposition

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