添加剂对微型活塞式内燃机铂丝炽热点火燃烧特性影响的实验研究

中文摘要: 针对微型活塞式内燃机采用铂丝炽热点火模式燃用甲醇、乙醇燃料时，失火率高、放热速率低、燃烧持续期长的问题，分别设计了添加硝基甲烷、双氧水添加剂的测试试验。硝基甲烷使着火时刻提前、燃烧速率加快、循环变动降低,而双氧水却使燃烧速率减慢、失火率升高。为分析硝基甲烷对铂丝炽热点火燃烧的助燃机理，分别设计了甲醇和乙醇混合不同比例硝基甲烷的测试试验。结果表明：硝基甲烷可调节燃烧始点从而影响甲醇、乙醇铂丝炽热点火燃烧的平均有效压力及其循环变动特征；硝基甲烷的添加所产生的燃烧始点的提前及燃烧持续期的缩短是循环变动降低的重要原因,但硝基甲烷比例过高时，铂丝炽热点火模式的燃烧始点位置分散、循环变动增大、动力性能下降。
Abstract:Combustion diagnosis results show that when using methanol or ethanol fuel,the miniature internal combustion engine with glow-ignition has higher level of cyclic variations, lower rate of heat release and longer combustion duration.So,adding additives of nitromethane and hydrogen peroxide were investigated.With the additive of nitromethane,the start of combustion (SOC) is advanced,the combustion velocity is improved and the coefficient of variation is reduced.However,the combustion characteristics become poor when the hydrogen peroxide is added to the fuel.In order to analyze the effects of nitromethane on the combustion,experiments of adding different proportions of nitromethane to methanol fuel and ethanol fuel were investigated.Under the glow-ignition condition with alcohol fuels,the nitromethane affects its indicated mean effective pressure and characteristic of cyclic variation by the adjustment of SOC.Adding nitromethane makes the SOC advance and let the combustion duration shorten that lead to the decrease of cycle-by-cycle variation. While with high proportion of nitromethane,the SOC tends to become more dispersed and the cycle-by-cycle variations become more severe,which result in performance degradation.