Experimental study of flame evolution, frequency and oscillation characteristics of steam diluted micro-mixing hydrogen flame
Experimental study of flame evolution, frequency and oscillation characteristics of steam diluted micro-mixing hydrogen flame
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DOI：
10.1016/j.fuel.2021.121078
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发表时间：
2021-10
期刊：
影响因子：
7.4
通讯作者：
Zhen Cao;Yajin Lyu;Jiangbo Peng;Penghua Qiu;Li Liu;Yang Chaobo;Yang Yu;Guang Chang;Biao Yan;Shaozeng Sun;Xin Yu
中科院分区：
文献类型：
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作者：
Zhen Cao;Yajin Lyu;Jiangbo Peng;Penghua Qiu;Li Liu;Yang Chaobo;Yang Yu;Guang Chang;Biao Yan;Shaozeng Sun;Xin Yu
在稀薄工况（等效比0.4 ~ 0.9）下，利用光学可及微混合燃烧室研究了蒸汽稀释对火焰演化、频率和振荡特性的影响。利用5 kHz OH平面激光诱导荧光（PLIF）显示火焰轮廓，并采用结构分区分析、频谱分析和动态模态分解（DMD）方法研究火焰不稳定性。研究了其对频移和热释放时空分布特性的影响。结果表明：随着氢当量比的增加，火焰长度逐渐延长，放热频率发生蓝移，但二次谐波频率仅发生在火焰臂区域；水蒸气含量对放热有明显的影响，稀释比为25%时存在明显的周期振荡。此外，蒸汽含量的增加或减少会使OH自由基浓度和分布发生显著变化，同时也会影响振荡区的强度和位置。模态分解分析表明，振荡区的增长与火焰臂区（FAZ）密切相关，并随着等效比的增大而过渡到火焰尾区（FTZ）。
Effects of steam dilution on flame evolution, frequency and oscillation characteristics were investigated using an optically accessible micro-mixing combustor under the lean operating condition (equivalence ratio 0.4 to 0.9). The flame profile was visualized by 5 kHz OH planar laser-induced fluorescence (PLIF), meanwhile the structural zoning analysis, frequency spectrum and dynamic mode decomposition (DMD) methods were used to investigate flame instability. The effects on frequency-shift and temporal-spatial heat-release distribution characteristics were demonstrated. Results indicated that heat-release frequency got blue-shift with the increase of hydrogen equivalence ratio while flame length gradually extended, though the second harmonic frequency only occurred in the flame arm zone. The steam content influenced the heat-release obviously, and the obvious periodic oscillation existed in the dilution ratio of 25%. Furthermore, the increasing or decreasing steam content will make the OH radical concentration and distribution change significantly, meanwhile the intensity and location of oscillation zone were also be influenced. The mode decomposition analysis revealed the growth of oscillation zone was closely related to the flame arm zone (FAZ) and experienced the transition to the flame tail zone (FTZ) with the increase of equivalence ratio.