Combustion Augmentation of Low Quality Fuel by Small Amount of Hydrogen

第一年、第二年明确了采用贫丙烷-空气和甲醇-空气混合气作为低品质燃料的定容燃烧室。(1)通过一个体积仅为主燃烧室1%的小凹腔喷射氢气-空气火焰，可以将当量比为0.6的混合气的燃烧持续时间缩短到与化学计量比混合气相同的持续时间。(2)此外，极稀混合气的燃烧持续期通过从体积仅为主燃烧室0.5%的较小空腔中喷射氢-氧火焰，可以将贫油（略低于贫油不燃极限）的燃烧时间缩短到与上述相同的持续时间。（国际动力工程会议）。今年上半年，研究了空腔内点火位置的影响。研究的目的是弄清楚自由基在氢射流火焰中的作用。在喷嘴处点火时，射流主要由燃烧气体组成，自由基浓度远小于在空腔底部点火时的自由基浓度。结果在JSME/KSME联合热工程会议上发表，得出的结论是，燃烧减少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，即由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。为了弄清射流火焰强化燃烧的主要因素（自由基或湍流），本文对射流火焰强化燃烧的机理进行了研究。在氢气火焰射流中加入等离子体射流。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IPC（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).