Sensitivity of LES-based harmonic flame response model for turbulent swirled flames and impact on the stability of azimuthal modes
Sensitivity of LES-based harmonic flame response model for turbulent swirled flames and impact on the stability of azimuthal modes
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DOI：
10.1016/j.proci.2014.07.021
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发表时间：
2015
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影响因子：
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通讯作者：
M. Bauerheim;G. Staffelbach;N. Worth;J. Dawson;L. Gicquel;T. Poinsot
中科院分区：
文献类型：
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作者：
M. Bauerheim;G. Staffelbach;N. Worth;J. Dawson;L. Gicquel;T. Poinsot
本文描述了剑桥环形燃烧室中方位不稳定模态的数值研究。LES用于计算谐波火焰响应模型（HFRM）和Helmholtz求解器来预测燃烧室的整体稳定性。HFRM量化了声学和湍流旋流火焰之间的相互作用。它们必须精确地知道，因为不稳定性对细微的变化非常敏感。本文采用大涡模拟方法，对20 °（N= 18）和30 °（N= 12）扇形进行了模拟，研究了方位角约束（对应于12或18个燃烧器的环形燃烧室）、热边界条件和燃料类型（甲烷或乙烯）对HFRM的影响。还计算了双扇区LES来研究火焰/火焰相互作用。这些基于LES的HFRM然后被用作Helmholtz求解器的输入，结果表明：（1）亚网格尺度LES模型导致谐波火焰响应的边际效应，而（2）方位角约束，热条件和燃料类型强烈影响火焰对声学的响应，因此控制方位角模式的稳定性。计算结果表明，甲烷环空实验应该是稳定的，而乙烯应该导致实验观察到的方位角不稳定模式。
This paper describes a numerical study of azimuthal unstable modes in the annular combustor of Cambridge. LES is used to compute a Harmonic Flame Response Model (HFRM) and a Helmholtz solver to predict the overall stability of the combustor. HFRM quantifies the interaction between acoustics and the turbulent swirled flames. They must be known with precision because instabilities are very sensitive to subtle changes. The effects of azimuthal confinement (corresponding to the annular combustor equipped with 12 or 18 burners), thermal boundary conditions and fuel type (methane or ethylene) on HFRMs are simulated here using LES of a single 20 degree (N= 18) or 30 degree (N= 12) sector. A double-sector LES is also computed to investigate flame/flame interactions. These LES-based HFRMs are then used as inputs for a Helmholtz solver and results show that (1) subgrid-scale LES models lead to marginal effects on the harmonic flame response while (2) azimuthal confinement, thermal conditions and fuel type strongly affect the flame response to acoustics and therefore control the stability of the azimuthal mode. Computations show that the annular experiment performed with methane should be stable while ethylene should lead to azimuthal unstable modes as observed experimentally.