电喷汽油机燃用甲醇/汽油混合燃料的燃烧特性

为了研究在汽油中掺混不同比例甲醇时对多点电喷汽油机燃烧放热规律的影响,通过实测示功图,对比分析了各种燃烧特征参数随发动机运行工况的变化规律。分析结果表明:在中、低转速时,甲醇/汽油混合燃料发动机的最高燃烧压力和最大压力升高率在中、小负荷时与汽油机基本相同,在大负荷时略高于汽油机;在高转速时混合燃料发动机的最高燃烧压力和最大压力升高率明显高于汽油机;在整个负荷范围内,混合燃料发动机的着火延迟期比汽油机的略长;混合燃料发动机的燃烧持续期在小负荷时比汽油机短,在中、大负荷时与汽油机基本相同;在中、小负荷时,汽油机的最大燃烧放热率和循环变动系数略高于混合燃料发动机,在大负荷时,两者基本相同;发动机转速对燃烧特征参数随掺混比的变化趋势没有明显的影响。

Combustion characteristics of electronic fuel injection gasoline engine fueled with methanol-gasoline blends

In order to study the effects of methanol-gasoline blends with different methanol ratios on the heat releasing rule of multi-point electric fuel injection gasoline engine,the recorded cylinder pressure of the engine was used to compare and analyze the variation rules of combustion characteristic parameters under the running conditions of the engine.Analysis result indicates that at middle and low engine speeds,the maximum cylinder pressure and the peak of pressure rising rate of blends engine are almost similar to those of gasoline engine under middle and light engine loads,and slightly higher under high engine loads;at high engine speeds,the peak pressure and the pressure rising rate of blends engine are evidently higher than those of gasoline engine.Compared with gasoline engine,the ignition delay period of the engine is longer under all range of loads;the combustion duration of the engine is shorter under light loads,and is the same under middle and high engine loads;the peak heat releasing rate and cyclic variability coefficient are slightly higher under middle and light loads,and are similar under high loads.There is not evident influence of engine speed on the varying trand of chmbustion characteristic parameters with the ratio of methanol in blends.