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Effects of Spark Component on Free Radical Formation in Spark Ignition Process of Combustible Mxture.

火花成分对可燃混合物火花点火过程中自由基形成的影响。

基本信息

批准号：
07650268
负责人：
UJIIE Yasusige
金额：
$ 1.47万
依托单位：
NIHON UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650268/
关键词：
Spark Ignitinn Combustible Mixture Free Radical Spark Energy Spectroscopic Analysis Gasoline Engine Spark Kernel 内燃機関予混合燃焼乱流場火花電極熱損失

项目摘要

Study on OH radical formation at the beginning of spark ignition has been performed experimentally. The purpose is to declare the effect of spark discharge on the initial formation of OH radical and the role of OH radical in the initiation of combustion chemical reaction. A double monochromator and an ultra-high-speed camera with a band pass filter were employed to observe the behavior of OH radical by its self-emission (306nm). The growth of a flame kernel was observed by schlieren photography with the ultra-high-speed camara. Propane-air premixture was used as a combustible gas : The concentration of propane was 4.7 vol% for all tests. Capacitance spark was employed to ignite premixtures. Electrodes were made of stainless steel and their diameter were 0.5 mm. Spark gap was adjusted to be 0.8 mm. The energy of spark was varied from 15 to 80 mJ.The behavior of OH radical was observed successfully from 1.2 to 40 mus after a spark discharge. The concentration of OH radical is high just after a spark discharge and decreases gradually from 10 mus. As spark energy increases, amount of OH radical formed at the beginning of spark ignition increases and growth rate of a flame kernel increases. It was found that, when the spark energy is large, there is little OH radical in the initial flame kernel and it exists near the edge of the initial flame kernel. From schlieren photographs of flame kernels, it was observed that high temperature region in the center of the flame kernel remains longer as spark energy increases. The life time of the high temperature region is longer than double the spark duration. It is suggested that this high temperature region accelerates the formation of OH radical at the boundary between the high temperature region and the propane-air premixture.

对火花点火开始时OH自由基的形成进行了实验研究。目的是揭示火花放电对OH自由基初始形成的影响以及OH自由基在引发燃烧化学反应中的作用。采用双单色仪和带有带通滤波器的超高速相机通过自发射（306nm）观察OH自由基的行为。使用超高速相机通过纹影摄影观察火焰核的生长。使用丙烷-空气预混合物作为可燃气体：所有测试中丙烷的浓度均为 4.7 vol%。采用电容火花来点燃预混物。电极由不锈钢制成，直径为0.5 mm。火花隙调整为0.8mm。火花能量从15到80 mJ变化。在火花放电后1.2到40 mus内成功观察到了OH自由基的行为。火花放电后OH自由基的浓度很高，从10μs开始逐渐降低。随着火花能量的增加，火花点火开始时形成的OH自由基的量增加，火焰核的生长速度增加。研究发现，当火花能量较大时，初始火焰核心中的OH自由基很少，且存在于初始火焰核心边缘附近。从火焰核的纹影照片可以看出，随着火花能量的增加，火焰核中心的高温区域保持的时间更长。高温区寿命比火花持续时间长一倍以上。这表明该高温区域加速了高温区域与丙烷-空气预混合物之间的边界处的OH自由基的形成。