空间时间分辨的多标量测量：方形通道中甲烷郁金香火焰
Spatiotemporally Resolved Multi-Scalar Measurements of Methane Tulip Flames in a Square Channel
AI总结：
研究通过多平面双色PLIF技术，空间时间分辨测量甲烷预混火焰在方形通道中郁金香结构的温度和OH浓度分布，揭示火焰形态演变及热损失机制。
摘要：
理解预混火焰在受限空间中的传播动力学对燃气管道消防安全和现代内燃机优化至关重要。在足够长的通道中，预混火焰常形成郁金香结构，但主导机制尚不明确，需要定量数据来改进郁金香火焰动力学的解释、表征和建模。本研究在约0.3大气压的方形通道中，研究了预混甲烷/空气混合物火焰，通过时间同步、多平面双色PLIF测量获得空间时间分辨的3D关键标量场数据集，包括温度和OH浓度，涵盖郁金香结构的形成与演变。显著的热损失抵消了燃烧释放的热量，产生近恒定压力环境。在热边界层中观察到OH浓度超平衡分布，表明热冷却主导化学松弛。此外，通过3D重建算法确定了五个代表性时间点的火焰前沿形态，提取了火焰表面积。本研究结果应有助于在现实边界条件下预混火焰传播动力学的理论建模和数值模拟。
英文摘要：
Understanding the propagation dynamics of premixed flames in confined spaces is important for fire safety in gas pipelines and for optimizing modern internal combustion engines. In sufficiently long channels, premixed flames routinely develop tulip flame structures, yet the dominant mechanism remains elusive, and quantitative data on the evolution of flame morphology and key scalar fields are critically needed to improve the explanation, characterization, and modeling of tulip flame dynamics. In this study, premixed flames of a stoichiometric methane/air mixture were investigated in a square channel at a reduced pressure of approximately 0.3 atm. Time-synchronized, multi-plane, dual-color PLIF measurements yielded a spatiotemporally resolved 3-D dataset of key scalar fields, including temperature and OH concentration, throughout the formation and evolution of the tulip structure. Significant heat loss across the walls counteracted the heat released by combustion, producing a near-constant-pressure environment throughout the experiment. A super-equilibrium distribution of OH concentration was observed in the thermal boundary layers, suggesting that thermal cooling dominated over chemical relaxation in those regions. Additionally, the flame-front morphology at five representative times was determined using a 3-D reconstruction algorithm, from which the flame surface area was extracted. The results of this study should aid theoretical modeling and numerical simulations of premixed flame propagation dynamics in confined spaces under realistic boundary conditions.
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