旋流火焰燃烧温度场二维吸收光谱诊断

Diode Laser Absorption Tomography for Swirling Flame Diagnostics

针对旋流火焰的复杂流场结构,结合可调谐二极管吸收光谱技术(tunable diode laser absorption spectroscopy , TDLAS)和多光谱层析成像术(hyperspectral tomography , HT),发展了具有空间分辨能力的二维吸收光谱测量技术(tunable diode laser absorption tomography , TDLAT),实现了甲烷/空气旋流火焰不同高度的二维温度场测量.该TDLAT系统吸收波长为7 185.6 , 7 444.3 , 6 807.8和7 466.3 cm -1 四线,采用分时-直接吸收探测策略,测量频率2.5 kHz ,采用13×13路正交光路(空间分辨率7 mm),采用模拟退火算法进行数据重建.经与理论计算结果对比分析,重建结果真实地反映了旋流火焰温度场的二维分布.

The swirl burner plays an important role in the aero-engine combustor.Accurate diagnosis of the heat release rate distribution is helpful for studying thermos-acoustic instabilities , flame shape transition and turbulence-chemistry interactions in the swirl flames.Tunable diode laser absorption spectroscopy (TDLAS) is a powerful tool with which to probe atoms and molecules non-intrusively and has been used in combustion diagnostics.Combined with hyperspectroscopy tomography (HT), TDLAS can improve its spatial resolution.The diagnostics system was composed of26 beams (13×13 , 13 parallel beams and 13 vertical beams).Four water vapor absorption lines , 7 185.6 , 7 444.3 , 6 807.8 , 7 466.3 cm -1 , were utilized in each beam using time-division-multiplexed method at total measuring frequency of2.5 kHz.A reconstruction routine based on simulated- annealing algorithm was used to reconstruct the two-dimensional distribution of temperature and H2O concentration.Comparisons with CFD simulations show that the reconstruction results reflect the real two-dimensional distribution of temperature in the swirl flame.