【作者】 王婧；

【导师】 徐宗俊； 张力；

【作者基本信息】 重庆大学 ， 机械制造及其自动化， 2007， 硕士

【摘要】 Power MEMS(MEMS-based power sources)即基于MEMS的微能源动力系统,在航空航天、通信、生物医学、国防等领域具有广阔的应用前景,将给现代社会带来重大而深远的影响。国内外已经相继开展了对它的研究,但是开展的研究大都着重于技术和工艺为题,在制约系统成败的关键为题,特别是如何实现微尺度燃烧等问题上的研究由于理论和试验模型的缺乏,仍然没有突破性的进展。微尺度燃烧是随着Power MEMS的出现而提出的,H2的微燃烧以及微燃烧室的研究都是当今的热点问题,国内开展这方面研究的单位还比较少。本论文以Jinsong Hua和Meng Wu等提出的管道型燃烧室模型和MIT微型涡轮机的燃烧室模型为研究对象,对Power MEMS微燃烧的数值模拟方法进行研究,基于微燃烧原理和特点,采用了合理的物理模型和数值计算方法,包括控制方程、化学反应动力学、物质传输理论、有限体积法及合理的边界条件等,用FLUENT软件及其用户子程序CHEMKIN系统地模拟了混合燃气的微燃烧情况,并与Jinsong Hua和Meng Wu等所得出的相关结论进行比较。本文第一部分对管道型燃烧室中的H2/air微燃烧进行了数值模拟,表明:燃烧室直径的增大可以使得燃烧更加完全,燃烧室效率增大;随着H2当量比的增大,燃烧室出口温度和平均反应速率都呈现先增大后减小的趋势;壁面散热对燃烧效率和速度影响非常大,而且燃烧室尺度越小,这种影响就越大;采用详细反应机理可以更精确地对燃烧室局部进行定量分析,而且模拟结果与Jinsong Hua和Meng Wu等得出的结论更加接近。本文第二部分对MIT微型涡轮机的燃烧室中的H2/air燃烧进行了数值模拟,表明:随着入口混合气体质量流量的增大,燃烧室效率出现先增大后减小的趋势,质量流量过小,气体可能在循环套内燃烧从而可能对壁面材料造成损坏;H2当量比在小于1的范围内增大,燃烧效率增大,但是如果当量比到一定数值后会产生在循环套内燃烧的情况,因此要选择合适的质量流量和H2当量比。虽然本文的是针对二维模型的计算,而且采用绝热壁面边界,但是同样可以反映Jinsong Hua和Meng Wu等得出的结论。更多还原

【Abstract】 Power MEMS is micro electromechanical system based power sources, which has extensive prospect in fields of airspace, communication, biomedicine, national defence and so on, and which will bring profound significance to the society. At present, there are many investigates into Power MEMS, but most of which emphasize technique and process. Due to lack of theory and test model, there are few breakthroughs in the field of micro-combustion. Micro -combustion is put forward after Power MEMS. And moreover, researches paid more and more attention into micro-combustion. There are few correlative researches inland.Based on the model of line type micro-scaled combustor and micro-scaled combustor in MIT turbine proposed by Jinsong Hua, This paper investigates into the method of numerical simulation for micro-combustion. Appropriate physical model and numerical methods that include control equation, chemical kinetics, transfer mechanism, the finite-volume method and reasonable boundary condition are employed. FLUENT and its user subprogram, CHEMKIN, are applied to simulate the micro-combustion of the mixture systematically. Besides that, the results of simulation are compared with those Jinsong Hua and Meng Wu obtained.In the first part of this paper, the micro-combustion of H2/air in the line type micro-scaled combustor is simulated and indicates that: with the diameter of combustor increasing, the combustion goes more completely; with the fuel ratio increasing, the exit temperature and the average rate of the chemical reaction rise originally and then fall off; loss of heat through the wall has great influence in the combustor efficiency and the rate of combustion, furthermore, the scale of the combustor is smaller, the influence is more evident; detailed chemical mechanics make the simulation result more quantitative, and the results are similar to what Jinsong Hua and Meng Wu got.Then in the second part, the micro-scaled combustor of the MIT turbine is simulated, and indicates that: with the mass flow of the mixture increasing, the combustor efficiency originally rises and then falls off. If the mass flow is too low, flame will occur in the circulation jacket and ultimately the wall may be damaged. With the fuel ratio increasing, the combustor efficiency increase. Once the ratio gets a certain value, flame will occur in the circulation jacket and then may damage the wall. Therefore, appropriate value of mass flow and the fuel ratio must be selected. Although two-dimensional model and adiabatic wall are applied, the results are reasonable as that Jingsong Hua got.更多还原