Burst-mode OH/CH2O planar laser-induced fluorescence imaging of the heat release zone in an unsteady flame.
Burst-mode OH/CH2O planar laser-induced fluorescence imaging of the heat release zone in an unsteady flame.
复制标题
DOI：
10.1364/oe.26.018105
复制
发表时间：
2018-06
期刊：
影响因子：
3.8
通讯作者：
U. Retzer;R. Pan;T. Werblinski;F. Huber;M. Slipchenko;T. Meyer;L. Zigan;S. Will
中科院分区：
文献类型：
--
作者：
U. Retzer;R. Pan;T. Werblinski;F. Huber;M. Slipchenko;T. Meyer;L. Zigan;S. Will
采用同步高速（7.5 kHz）平面激光诱导荧光法（PLIF）对甲醛（CH2O）和羟基自由基（OH）在CH4/O2/N2非预混非定常火焰中的火焰结构和放热区进行了可视化研究。为此，设计用于高速运行的染料激光器被Nd:YAG爆发模式激光器的532 nm的二次谐波输出泵浦，以产生可调谐的566 nm光束。在频率加倍后，在283 nm处使用大约2.2 mJ/脉冲的高能量khz率窄带脉冲序列来激发OH自由基。同时，CH2O被相同Nd:YAG激光器的三倍频输出激发，在高脉冲能量（bbb100 mJ/脉冲）下提供持续时间超过10 ms的高频脉冲串。激发能使CH2O和OH PLIF的信噪比（SNRs）分别达到~10和~60，使用单个高速增强型CMOS相机配备图像倍频器。这允许足够的信噪比来研究主放热区和局部火焰结构在kHz速率下的时间演变，从OH-和CH2O-PLIF信号的空间重叠。
The paper presents simultaneous high-speed (7.5 kHz) planar laser-induced fluorescence (PLIF) of formaldehyde (CH2O) and the hydroxyl-radical (OH) for visualization of the flame structure and heat release zone in a non-premixed unsteady CH4/O2/N2 flame. For this purpose, a dye laser designed for high-speed operation is pumped by the second-harmonic 532 nm output of a Nd:YAG burst-mode laser to produce a tunable, 566 nm beam. After frequency doubling a high-energy kHz-rate narrowband pulse train of approximately 2.2 mJ/pulse at 283 nm is used for excitation of the OH radical. Simultaneously, CH2O is excited by the frequency-tripled output of the same Nd:YAG laser, providing a high-frequency pulse train over 10 ms in duration at high pulse energies (>100 mJ/pulse). The excitation energies enable signal-to-noise ratios (SNRs) of ~10 and ~60 for CH2O and OH PLIF, respectively, using a single high-speed intensified CMOS camera equipped with an image doubler. This allows sufficient SNR for investigation of the temporal evolution of the primary heat release zone and the local flame structure at kHz rates from the spatial overlap of the OH- and CH2O-PLIF signals.