毕业设计（论文）中英文摘要 毕业设计（论文）题目，黑体小五号字。 四号黑体 二甲醚清洁燃料均质压燃燃烧数值模拟研究
摘要
空一行 摘要前需有论文题目，三号黑体居中，上下各空一行。 均质充量压缩着火（HCCI）燃烧，作为一种能有效实现高效低污染的燃烧方式，能够使发动机同时保持较高的燃油经济性和动力性能，而且能有效降低发动机的NOx和碳烟排放。此外HCCI燃烧的一个显著特点是燃料的着火时刻和燃烧过程主要受化学动力学控制，基于这个特点，发动机结构参数和工况的改变将显著地影响着HCCI发动机的着火和燃烧过程。本文以新型发动机代用燃料二甲醚（DME）为例，对HCCI发动机燃用DME的着火和燃烧过程进行了研究。研究采用由美国Lawrence Livermore国家实验室提出的DME详细化学动力学反应机理及其开发的HCT化学动力学程序，且DME的详细氧化机理包括399个基元反应，涉及79个组分。为考虑壁面传热的影响，在HCT程序中增加了壁面传热子模型。采用该方法研究了压缩比、燃空当量比、进气充量加热、发动机转速、EGR和燃料添加剂等因素对HCCI着火和燃烧的影响。结果表明，DME的HCCI燃烧过程有明显的低温反应放热和高温反应放热两阶段；增大压缩比、燃空当量比、提高进气充量温度、添加H2O2、H2、CO使着火提前；提高发动机转速、采用冷却EGR、添加CH4、CH3OH使着火滞后。
空一行 关键字：均质充量压缩着火，化学动力学，数值模拟，二甲醚，EGR，燃料添加剂
摘要正文五号宋体，首行缩进二个字，字数300－500字，单倍行距。 小四号黑体 五号宋体，逗号分开，最后一个关键字后面无标点符号。
NUMERICAL SIMULATION OF HOMOGENEOUS CHARGE COMPRESSION IGNITION COMBUSTION
FUELED WITH DIMETHYL ETHER 四号Times New Roman居中加黑 ABSTRACT 三号Times New Roman居中加黑，一律用大写字母，上下各空一行。 空一行
五号Times New Roman, 首行缩进，单倍行距。 HCCI (Homogenous Charge Compression Ignition) combustion has advantages in terms of efficiency and reduced emission. HCCI combustion can not only ensure both the high economic and dynamic quality of the engine, but also efficiently reduce the NOx and smoke emission. Moreover, one of the remarkable characteristics of HCCI combustion is that the ignition and combustion process are controlled by the chemical kinetics, so the HCCI ignition time can vary significantly with the changes of engine configuration parameters and operating conditions. In this work numerical scheme for the ignition and combustion process of DME homogeneous charge compression ignition is studied. The detailed reaction mechanism of DME proposed by American Lawrence Livermore National Laboratory (LLNL) and the HCT chemical kinetics code developed by LLNL are used to investigate the ignition and combustion processes of an HCCI engine fueled with DME. The new kinetic mechanism for DME consists of 79 species and 399 reactions. To consider the effect of wall heat transfer, a wall heat transfer model is added into the HCT code. By this method, the effects of the compression ratio, the fuel-air equivalence ratio, the intake charge heating, the engine speed, EGR and fuel additive on the HCCI ignition and combustion are studied. The results show that the HCCI combustion fueled with DME consists of a low temperature reaction heat release period and a high temperature reaction heat release period. It is also founded that increasing the compression ration, the equivalence ratio, the intake charge temperature and the content of H2O2, H2 or CO cause advanced ignition timing. Increasing the engine speed, adoption of cold EGR and the content of CH4 or CH3OH will delay the ignition timing.
Key words: HCCI, chemical kinetics, numerical simulation, DME, EGR, fuel additive 五号Times New Roman，各关小四号Times New Roman加黑,key words之间加一空格 。 键词之间逗号分开，逗号后加一空格。
空一行 目 录 五号宋体,单倍行距 三号黑体居中
第一章 绪论----------------------------------------------------------------------------------------------1 1.1 引言-----------------------------------------------------------------------------------------------1 1.2 HCCI的数值模拟研究现状------------------------------------------------------------------1
1.2.1 HCCI数值模拟模型---------------------------------------------------------------------1 -------------------------------------------------------------------
第二章 DME均质充量压燃着火的数值模拟方法------------------------------------------------2 2.1 二级标题-----------------------------------------------------------------------------------------2
2.1.1 三级标题----------------------------------------------------------------------------------2 ------------------------------------------------------------------- -------------------------------------------------------------------
第五章 结论----------------------------------------------------------------------------------------------4 参考文献---------------------------------------------------------------------------------------------------5 致谢---------------------------------------------------------------------------------------------------------6 译文及原文------------------------------------------------------------------------------------------------7
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