An experimental study on the ignition ability of a laser-induced gaseous breakdown
An experimental study on the ignition ability of a laser-induced gaseous breakdown
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DOI：
10.1016/j.combustflame.2017.01.016
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发表时间：
2017-04
影响因子：
4.4
通讯作者：
T. Endo;Y. Takenaka;Y. Sako;T. Johzaki;S. Namba;D. Shimokuri
中科院分区：
文献类型：
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作者：
T. Endo;Y. Takenaka;Y. Sako;T. Johzaki;S. Namba;D. Shimokuri
为了考察激光点火的能力，在定容燃烧室中，利用一对电极和汽车火花驱动器产生的火花、聚焦高功率激光产生的火花以及聚焦高功率激光在一对假电极之间产生的火花，对静止的贫燃料丙烷-空气混合气进行了点火实验，在所有情况下，进入气体中的沉积能量是相同的。在实验中，改变混合气中燃料的摩尔分数，获得了燃烧室内壁压力历程、点火成功概率以及点火过程的高速多帧纹影图像。结果表明，在接近点火极限的贫燃料条件下，激光诱导火花的点火能力上级常规电火花，激光的点火能力越强诱发火花的原因不仅是由于电极缺乏热损失，而且是由于初始火焰核很大，其有效能量因吸入燃烧室的可燃混合物的快速放热而增加。核由激光诱导火花产生的非球形向内流动形成。此外，透射激光再注入等离子体增强了激光的点火能力。这主要是由于总吸收能量的增加。
For examining the ability of laser ignition, a quiescent lean-fuel propane–air mixture was ignited in a constant-volume chamber by a spark induced by a pair of electrodes and an automotive spark driver, a spark induced by focused high-power laser, or a spark induced by focused high-power laser between a pair of dummy electrodes, where the deposited energy into the gas was the same in all cases. In the experiments, the mole fraction of the fuel in the mixture was varied, and the pressure history on the inner wall of the chamber, probability of successful ignition, and the high-speed multi-frame schlieren images of an ignition process were obtained. The results showed that the ignition ability of a laser-induced spark was superior to that of a conventional electrical spark in lean-fuel conditions near the ignitable limit, and that the higher ignition ability of a laser-induced spark was due not only to the lack of heat loss to electrodes but also to a large initial flame kernel whose effective energy was augmented by rapid heat release from the combustible mixture sucked into the kernel by a non-spherical inward flow created by a laser-induced spark. In addition, reinjection of the transmitted laser light into plasma strengthened the ignition ability of the laser. This was predominantly due to the increase of the total absorbed energy.