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首页> 外文期刊>Experimental Thermal and Fluid Science: International Journal of Experimental Heat Transfer, Thermodynamics, and Fluid Mechanics >Experimental study of turbulent flame kernel propagation
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Experimental study of turbulent flame kernel propagation

机译：湍流火焰核扩散的实验研究

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Flame kernels in spark ignited combustion systems dominate the flame propagation and combustion stability and performance. They are likely controlled by the spark energy, flow field and mixing field. The aim of the present work is to experimentally investigate the structure and propagation of the flame kernel in turbulent premixed methane flow using advanced laser-based techniques. The spark is generated using pulsed Nd:YAG laser with 20 mJ pulse energy in order to avoid the effect of the electrodes on the flame kernel structure and the variation of spark energy from shot-to-shot. Four flames have been investigated at equivalence ratios, phi(j), of 0.8 and 1.0 and jet velocities, U-j, of 6 and 12 m/s. A combined two-dimensional Rayleigh and LIPF-OH technique has been applied. The flame kernel structure has been collected at several time intervals from the laser ignition between 10 mu s and 2 ms. The data show that the flame kernel structure starts with spherical shape and changes gradually to peanut-like, then to mushroom-like and finally disturbed by the turbulence. The mushroom-like structure lasts longer in the stoichiometric and slower jet velocity. The growth rate of the average flame kernel radius is divided into two linear relations; the first one during the first 100 mu s is almost three times faster than that at the later stage between 100 and 2000 mu s. The flame propagation is slightly faster in leaner flames. The trends of the flame propagation, flame radius, flame cross-sectional area and mean flame temperature are related to the jet velocity and equivalence ratio. The relations obtained in the present work allow the prediction of any of these parameters at different conditions. (C) 2007 Elsevier Inc. All rights reserved.
机译：火花点火燃烧系统中的火焰核控制着火焰的传播，燃烧的稳定性和性能。它们可能受到火花能量，流场和混合场的控制。本工作的目的是使用先进的基于激光的技术，通过实验研究湍流预混甲烷流中火焰核的结构和传播。使用具有20 mJ脉冲能量的Nd：YAG脉冲激光产生火花，以避免电极对火焰核结构的影响以及每次发射时火花能量的变化。已经研究了四种火焰，当量比phi（j）为0.8和1.0，射流速度U-j为6和12 m / s。结合了二​​维瑞利和LIPF-OH技术。从10毫秒至2毫秒之间的激光点火，已以几个时间间隔收集了火焰核结构。数据表明，火焰核的结构从球形开始，逐渐变为花生状，然后变为蘑菇状，最后受到湍流的干扰。蘑菇状结构的化学计量持续时间较长，射流速度较慢。平均火焰核半径的增长率分为两个线性关系：第一个100毫秒内的第一个速度比后面的100到2000毫秒内的速度快三倍。在较稀薄的火焰中，火焰传播的速度略快。火焰传播，火焰半径，火焰横截面积和平均火焰温度的趋势与射流速度和当量比有关。在本工作中获得的关系允许在不同条件下预测这些参数中的任何一个。 （C）2007 Elsevier Inc.保留所有权利。

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