【摘要】 使用二甲醚燃料微引燃汽油混合燃烧过程可以改善汽油高稀释燃烧的可控性,并进一步改进其热效率.为了从机理上研究微引燃混合燃烧过程,构建了一个可以兼顾不同DME-PRF掺混比例的化学反应动力学简化模型.通过层级扩展的方式,从CO/H2内核基团的反应开始,在此基础上逐步加入C1~C3过渡反应机理模块,以及C4~C7/C8的PRF子机理和DME子机理模块.最终得到一个包含79种组分267个基元反应的多组分替代燃料简化机理.激波管实验验证结果表明,该机理可以较准确地预测不同温度、压力、当量比下单一燃料和混合燃料的着火延迟;发动机实验证明,该机理对于着火相位和放热率有着不错的预测效果.更多还原

【Abstract】 The controllability of gasoline high dilution combustion process can be improved considerably with dimethyl ether(DME)micro flame ignition,as well as its thermal efficiency.In order to research mechanism of micro flame ignition combustion process,a reduced DME-PRF(primary reference fuel)blended mechanism applicable to different mixing proportion was proposed.The present DME-PRF multi-surrogate fuel chemical kinetic mechanism was assembled in a hierarchal manner.Starting from small radicals and molecules(C0—C1),larger molecules such as C1—C3 transition reaction module,C4—C7/C8 PRF subset and DME subset were added into it gradually.The blended fuel mechanism consists of 79 species and 267 reactions.Combustion experiments of blends of PRF and DME in a shock tube were conducted.The reduced blended fuel mechanism in this work was well validated by ignition delay comparison with the experimental data in a shock tube over extensive ranges of equivalence ratio,temperature and pressure for each single fuel component and their blends.Simulations of a HCCI engine in CFD were also conducted.The results indicate overall satisfactory agreements between the simulation results and experimental data.更多还原