醇类-汽油混合燃料的喷雾特性

在试验台上,研究了使用汽油醇类混合燃料,其中醇类燃料体积分数分别为10％的乙醇-汽油、30％的乙醇-汽油、10％的正丁醇-汽油和30％的正丁醇-汽油时,直喷汽油机多孔喷油器的喷油率和喷雾特性.结果表明,随着喷油压力的提高,醇类-汽油混合燃料的瞬时喷油率增大,且瞬时喷油率波动性依赖于燃料.同时,喷油压力的提高使得喷雾贯穿距离加大,单次喷油后同一时刻的喷雾差异性变大.在高背压,相同喷油压力下醇类-汽油混合燃料的贯穿距离与汽油接近.背压大小对不同燃料喷油初期的喷雾锥角影响较大.低背压时,汽油的喷雾锥角高于醇类-汽油混合燃料,而高背压时,除了30％乙醇-汽油燃料外,醇类-汽油混合燃料的喷雾锥角更大.

Spray Characteristics of Various Alcohol-Gasoline Blends

The spray characteristics and fuel injection rate of a multi-hole injector of a direct injection gasoline engine were investigated on test benches when the alcohol-gasoline blends containing 10% and 30% volume fraction of ethanol,10% and 30% volume fraction of n-butanol and their base gasoline were used,respectively.The results show that,with the increase of injection pressure,the transient fuel injection rates of alcohol-gasoline blends increase,and their variations are dependent on the fuels tested.In the meantime,spray penetration of various fuels increases with injection pressure,and the differences of individual spray image at the same time in a single injection increase.The spray penetration of alcohol-gasoline blends is close to that of gasoline at high ambient pressure.The spray cone angles of different fuels after the initial stage of injection are much affected by ambient pressure in the constant chamber.At low ambient pressure,the spray cone angles of gasoline are greater than those of alcohol-gasoline blends.On the contrary,at high ambient pressure,the spray cone angles of alcohol-gasoline blends are bigger than those of gasoline except the case in which the blends containing 30% volume fraction of ethanol are used.