Combustion Augmentation of Low Quality Fuel by Small Amount of Hydrogen

第一年，第二年明确使用稀丙烷-空气和甲醇-空气混合物作为定容燃烧室的低质量燃料。(1)在体积仅为主燃烧室1%的极小空腔中，氢气火焰射流可以将当量比为0.6的混合气的燃烧持续期缩短到与化学计量混合气相同的持续期。(2)利用体积仅为主燃烧室体积0.5%的氢氧火焰射流，可以将稀薄混合气(略低于可燃稀薄极限)的燃烧持续期缩短到与上述相同的持续期。这些结果在1992年国际动力工程会议上进行了讨论。这项研究的目的是弄清楚自由基在氢气喷射火焰中的作用。当在喷嘴点火时，大部分射流由燃烧气体组成，预计自由基浓度比在空腔底部点燃的要小得多。在JSME/KSME联合热工程会议上公布的结果表明，燃烧降低的趋势可以用自由基效应来解释，但更容易用射流强度的效应来解释，即强射流在主燃烧室中产生的湍流。今年下半年，在相同的射流火焰速度下，研究了射流火焰中自由基浓度的影响。这是为了更清楚地了解一种射流火焰增强燃烧的主要因素(自由基或湍流)。等离子体射流也被添加到氢焰射流中。结果表明，自由基的影响是次要因素，氢射流火焰强度是缩短燃烧持续期的主要因素。研究结果将在第七届国际太平洋汽车工程大会上公布。

The first year, next items were made clear using lean propane-air and methanol-air mixture as a low quality fuels with constant volume combustion chamber. (1) The combustion duration of mixture whose equivalence ratio is 0.6 can be reduced to the same duration as stoichiometric mixture by a hydrogen-air flame jet from a very small cavity whose volume is only 1% of main chamber. (2) Moreover, the combustion duration of very lean mixture (a little leaner than the lean limit of in-flammability) can be reduced to the same duration as mentioned above by a hydrogen-oxygen flame jet from the smaller cavity whose volume is only 0.5% of main chamber.Those results were discussed at the 1992-IPEC(International Power Engineering Conference).In the first half of this year, the effect of ignition location in the cavity was studied. The objective of the research was to make clear the effect of radicals in hydrogen jet flames. When it is ignited at the nozzle, most of jet is composed by burnt gas and the concentrations of radicals are expected much less than that ignited at the bottom of the cavity. The results were presented at the JSME/KSME joint thermal engineering conference and it was concluded that the tendency of reduction of combustion could be explained by the radical effect but it is easier to explain by a effect of jet strength, namely turbulence in a main chamber generated by the strong jet.In the last half of this year, the effect of radical concentrations in jet flame was investigated under the same jet flame speeds. It was performed to make clearer the main factor (radicals or turbulence) of combustion augmentation done by a kind of jet flame. The plasma jet was also added into the hydrogen flame jet. The result showed that the effects of radicals are minor factors and the strength of the hydrogen jet flame is the main factor that can reduce combustion duration. The results will be presented at the 7th IPC (International Pacific Congress on Automotive Engineering).