氧含量和压力对柴油自燃行为的影响

在定容燃烧弹系统上,研究了柴油在不同氧含量和不同压力条件下的喷射自燃行为。采用十六烷值改进剂硝酸异辛酯(EHN)、含氧组分聚甲氧基二甲醚(DMMn)和高密度燃料(HDF)与基础柴油复配,研究了不同复配柴油的十六烷值特性和在不同压力下的燃烧特性。结果表明：氧含量和压力的下降会使柴油的着火滞后期和燃烧滞后期延长,燃烧滞后期对氧含量的敏感性大于压力的变化;当压力下降时,柴油燃烧的压力升高最大值会降低;当氧含量下降时,在一定压力范围内压力升高最大值会随氧含量下降而升高;复配柴油的燃烧滞后期和动态十六烷值对压力变化的敏感性与柴油的组成密切相关。柴油热值严重影响燃烧的压力升高值,通过加大喷油量可有效提高压力升高最大值。

Effects of Oxygen Content and Pressure on the Spontaneous Combustion of Diesel

Jet spontaneous combustion of diesel was investigated in a constant volume combustion bomb system under different oxygen contents and different pressure conditions. The cetane improver isooctyl nitrate (EHN), the oxygen-containing component polymethoxy-dimethyl ether (DMMn) and high-density fuel (HDF) were compounded with basic diesel to study the characteristics of cetane number of different compounded diesels and combustion characteristics under different pressures. The results show that decrease of oxygen content and pressure will prolong the ignition lag phase and combustion delay period of diesel, and the sensitivity of combustion delay time period to oxygen content is greater than that to pressure change. When the pressure drops, the maximum pressure increase of diesel combustion will decrease; when oxygen content drops, it can increase with the decrease of oxygen content within a certain pressure range. The sensitivity of compounded diesel fuels′ combustion delay period and dynamic cetane number to pressure change is closely related to diesel composition. In addition, the heat value of diesel seriously affects pressure increase during combustion, and the maximum pressure increase can be effectively improved by increasing fuel injection.