燃料结构和醇类含氧燃料对碳烟生成过程影响的多维数值模拟  

Multi-Dimensional Numerical Simulation on the Effects of Fuel Structure and Oxygenated Alcohol Fuels on Soot Formation Process

作　　者：王浒[1] 郑尊清[1] 尧命发[1] 

机构地区：[1]天津大学内燃机燃烧学国家重点实验室,天津300072

出　　处：《内燃机学报》2016年第2期117-124,共8页Transactions of Csice

基　　金：国家自然科学基金国际合作与交流资助项目(51320105008)

摘　　要：采用多维数值模拟研究方法系统研究了燃料结构和不同醇类燃料对定容燃烧弹中正庚烷喷雾燃烧过程中碳烟生成过程的影响.研究结果表明:在高温高压条件下,燃料物性对喷雾破碎和蒸发过程影响较小,滞燃期和含氧量是影响混合过程和碳烟排放的主要因素;正十二烷的碳烟生成量远高于正庚烷,PRF20(80%,正庚烷+20%,异辛烷,质量比)的碳烟生成量与正庚烷接近;甲醇、乙醇和正丁醇燃料的含氧与促进混合共同作用可显著降低正庚烷/醇类掺混燃料的碳烟体积分数;与正庚烷和PRF20燃料相比,含氧作用是B20(80%,正庚烷+20%,正丁醇)燃料降低碳烟排放的主要因素;M20(80%,正庚烷+20%,甲醇)和E20(80%,正庚烷+20%,乙醇)的滞燃期和火焰浮起长度长,含氧量也相对较高,与此对应其碳烟生成量也较低,M20燃料的碳烟最少;在E20的滞燃期和火焰浮起长度均比M20略长的情况下,得益于甲醇较高的含氧量和C—O分子结构,相同质量掺混比例条件下正庚烷/甲醇掺混燃料降低碳烟的效果更明显.Numerical study was conducted to study the effects of fuel structure and oxygenated alcohol fuels on soot formation process under the mixing-controlled spray combustion condition in a constant volume bomb.Results show that,physical properties of fuel have slight effect on the spray breakup and evaporation processes.Ignitibility and oxygen content will dominate the mixing and soot formation processes.Soot in n-dodecane spray is much higher than that in n-heptane,while the soot from PRF20（mixture of 80%, n-heptane and 20%,iso-octane,mass ratio）is similar to that from n-heptane.The improvement in mixing due to increased ignition delay and oxygen content in fuel molecule for mixtures of n-heptane/methanol（M20）,n-heptane/ethanol（E20）and n-heptane/n-butanol（B20）are the main reasons for soot reduction compared with neat n-heptane.The oxygen content in B20 is responsible for the soot reduction compared with n-heptane and PRF20.Soot in M20 and E20 sprays shows the lowest because of the increased ignition delays and lift-off lengths,as well as higher oxygen content.Although the predicted ignition delay and lift-off length of E20 are longer than those of M20,the soot reduction effect with M20 is still greater than that with E20,and this is attributed to the higher oxygen content and directly bonded C—O bond in methanol molecule.

关 键 词：喷雾燃烧 碳烟 燃料特性 醇类含氧燃料 多维数值模拟 

分 类 号：TK421.2[动力工程及工程热物理—动力机械及工程]