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Optical diagnostics of nanosecond and nanometer ignition and quenching mechanism

纳秒和纳米点火和淬灭机制的光学诊断

基本信息

批准号：
18360102
负责人：
TOMITA Eiji
金额：
$ 10.66万
依托单位：
Okayama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18360102/
关键词：
Laser Ignition Plasma Spectroscopic Measurement Premixed Flame LIBS 自発光

项目摘要

The laser-induced breakdown was generated by focusing a 532-nm nanosecond pulse from a Q-switched Nd:YAG laser. In this research, 1) Laser ignition charcteristics, such as, shape of laser-induced plasma, emission spectra, breakdown threshold energy, flame kernel development, minimum ignition energy, 2) Effect of ambient pressure on laser-induced plasma, 3) Shockwave from laser-induced plasma, and Flow structure around hot kernel, 4) Application of laser-induced breakdown spectroscopy (LIBS) on premixed flame and exhaust gas from spark-ignition engine, were investigated. The results provided information about the different stages of laser-induced breakdown; with a specific attention on the transition from flame kernel to self sustain flame. The plasma shape and emission spectrum were very reproducible. The differences in flame kernel size and radicals emission evolution were analyzed in case of mixture firing or misfiring. Under higher ambient pressure conditions, energy for making laser-induced plasma decreases. Based on the flame kernel size evolution the Taylor Blast wave theory has been utilized to plot the location of the shock. The location was calculated with the laser supported detonation (LSD) Model. Furthermore, a very good correlation has been observed with the hot gas ignition process. The atomic spectrum intensity of the exhaust gas changed with preset A/F. When A/F becomes larger (lean condition), C and Fl spectrum intensity decreased because these atomic decreased because these atomics comes from fuel (regular gasoline) in premixed flame and exhaust gas from SI engine. Atomic spectrum intensity ratios of H/0 and C/O correlated with preset A/F.

激光诱导击穿是通过聚焦来自Q开关Nd：YAG激光器的532 nm纳秒脉冲产生的。本文研究了激光点火特性，如激光诱导等离子体的形状、发射光谱、击穿阈值能量、火焰核的发展、最小点火能量等; 2）环境压力对激光诱导等离子体的影响; 3）激光诱导等离子体产生的冲击波以及热核周围的流动结构，4）研究了激光诱导击穿光谱（LIBS）技术在火花点火发动机预混火焰和排气中的应用。结果提供了有关激光诱导击穿的不同阶段的信息，特别注意从火焰核到自持火焰的过渡。等离子体形状和发射光谱是非常可重复的。分析了混燃和拒燃两种情况下火焰核尺寸和自由基释放的差异。在较高的环境压力条件下，用于产生激光诱导等离子体的能量降低。根据火焰核尺寸的演变，泰勒爆炸波理论已被用来绘制的冲击波的位置。采用激光支持爆轰（LSD）模型计算了爆轰点的位置。此外，一个非常好的相关性已被观察到与热气体点火过程。废气的原子光谱强度随预设的A/F而变化。当A/F变大时（稀燃状态），C和F1光谱强度降低，因为这些原子减少，因为这些原子来自预混火焰中的燃料（普通汽油）和SI发动机的废气。H/O和C/O的原子光谱强度比与预设的A/F相关。