【作者】 朱林；

【导师】 孔凡让；

【作者基本信息】 中国科学技术大学 ， 精密机械与仪器， 2008， 博士

【摘要】 基于燃烧的微发电系统是一种新概念的电池,它将一个发电过程集成在数十立方厘米甚至数立方厘米的空间内,具有化学电池无法比拟的优越性,因此,成为目前世界各国关注和竞相研究的焦点和热点。本文以美国麻省理工学院研制的硅基六晶片微燃烧器为研究对象,采用数值计算的方法,开展小/微燃烧理论和技术,微燃烧器结构设计方面的应用基础性研究,主要包括如下内容:1、硅基六晶片微燃烧器燃烧特性的研究以氢气/空气为混合燃料,采用考虑了基元反应动力学机理燃烧程序的二维CFD数值分析方法,主要研究微尺度下燃料混合当量比、燃料流速、燃烧器壁墙传热系数对该尺度燃烧器燃烧特性的影响,重点探讨该燃烧器发生熄火、回燃的症结,并将所计算的结果与美国麻省理工学院的实验结果进行比较,以检验所使用方法的正确性。2、微燃烧器结构的虚拟装配技术的研究通过对目前微燃烧器结构设计方法的研究,提出利用机械虚拟装配技术完成微燃烧器的结构设计,主要研究利用基于特征的零件实体建模技术构建微燃烧器各个晶片的方法,研究利用虚拟装配技术模拟具体实际装配过程完成微燃烧器结构的方法、研究采用干涉检验技术、爆炸技术检查整个燃烧器结构正确性的方法,并将所研究的结果与新加坡高性能研究所构建微燃烧器的方法进行对比,以验证所研究方法的正确性、可行性和优越性。3、微燃烧器的结构失效的研究在上述燃烧器燃烧特性、结构设计的研究基础上,以硅基六晶片微燃烧器为研究对象,采用理论和数值计算相结合的方法,在不考虑微燃烧器加工过程中残余应力的前提下(由于实验经费、实验设备的缺乏),首先,在不发生回燃、发生回燃两种情形下,分别对微燃烧器结构进行应力、应变分析,然后引入机械模糊可靠性设计方法预测该燃烧器的结构寿命,并将所计算的结果与美国麻省理工学院的实验结果进行比较,以检验所使用方法的正确性。综上所述,本文提出利用二维CFD数值计算方法,在考虑多步基元化学反应机理的基础上,研究微尺度燃烧器燃烧特性及火焰的稳燃机理;提出利用机械虚拟装配技术构建微燃烧器的结构,并在此基础上,对处于运行过程中的微燃烧器结构进行应力、应变分析,最后,提出利用机械模糊可靠性设计方法估算微燃烧器的寿命,探索了一套研究微尺度燃烧器的新思路和新方法,为以后微尺度燃烧器性能优化打下坚实的基础。更多还原

【Abstract】 The combustion-based micro-power device, such as a micro-gas turbine engine, is considered as a novel battery, because it can produce power in a volume less than from several cubic centimeters to dozens of cubic centimeters. It is its excellent advantages over other batteries that make itself attracted by all the countries around the world. Having analyzed the above, the objective of the thesis is to perform numerical simulations to analyse the performance of the micro-combustor under various conditions based on the prototype used in the MIT micro-gas turbine, such as its combustion behaviour, stress and strain condition as well as evaluating its fatigue life. The thesis is specifically intended to1) analyze the combustion behaviour of a six-wafer micro-combustor. In detail, firstly we performed a two-dimensional numerical simulation to investigate the effect of various conditions, say, the hydrogen/air ratio, the hydrogen/air mass flow rate and the heat loss through the outer wall of the micro combustor, and then we compared the computing results above with the experimental studies on the micro combustor from MIT in order to verify whether or not the approaches used in the thesis are right.2) assemble the micro-combustor based on virtual assembly techniques. Based on the prototype used in the MIT micro-gas turbine engine, an idea of creating its three-dimensional micro-combustor with virtual assembly technique was proposed after analyzing the traditional approaches of geometric modeling in the field of CFD. In detail, the theory and the process of virtual assembly techniques were firstly depicted, and then the three-dimensional micro-combustor was constructed to demonstrate the idea in SolidWorks with virtual design techniques, such as modeling techniques based on features, virtual assembly techniques and the exploded view. Lastly, the structure of a micro-combustor created in the thesis is compared with the one made in Singapore to verify whether or not the approaches used in the thesis are right.3) study the failure occurring on the micro-combustor. Based on the combustion behaviour of a micro-combustor, either theoretic or computational approaches were performed to study the failure on the micro-combustor without regard to the residual stress from the fabrication process. In detail, FEA was firstly performed to.investigate the structure of a micro-combustor either in non- burning in the recirculation jacket or burning in the recirculation jacket. And then fuzzy probability was employed to evaluate the fatigue life of the micro-combustor. Lastly, the computing results above is compared with the experimental studies on the micro combustor from MIT in order to verify whether or not the approaches used in the thesis are right.In general, a two-dimensional numerical simulation was performed to investigate the effect of various conditions in view of 19 reversible elementary reactions and nine species; an idea of creating the three-dimensional micro-combustor with virtual assembly techniques was proposed after analyzing the traditional approaches of geometric modeling in the field of CFD; either theoretic or computational approaches were performed to study the failure on the micro-combustor without regard to the residual stress from the fabrication process. The objective we try to do in the thesis is to seek a new approach to design a micro-combustor in order to build up a solid foundation to optimize the micro-combustor.更多还原