【作者】 刘庆；

【导师】 王谦；

【作者基本信息】 江苏大学 ， 工程热物理， 2008， 硕士

【摘要】 自由活塞发动机结构简单,更适合向微型化发展,将均质充量压燃方式(Homogeneous Charge Compress Ignition,HCCI)这种新型燃烧方式与微型自由活塞式发动机相结合,不仅可以解决微燃烧室壁面的火焰淬熄问题,同时可以解决HCCI所面临的着火控制难的问题,另外,微型自由活塞发动机的能量转化为电能的效率高。因此,开展基于HCCI燃烧方式的微型自由活塞式发动机的研究,有望突破目前燃烧室尺寸微小化带来的燃烧限制瓶颈,对开发微型动力机电装置具有重要意义。本文针对微型HCCI自由活塞发动机的工作特点,分别建立了完全理想条件下(即绝热、无漏气)微HCCI自由活塞发动机燃烧过程的二维模型,以及考虑传热和漏气影响的二维模型。依据活塞运动速度与其所受压力的相互关系,应用STAR-CD中的多个子程序实现了活塞运动过程与缸内气体化学动力学的耦合,建立了模拟活塞工作过程的动网格程序。使用STAR/KINetics软件,即CFD软件STAR—CD与详细化学动力计算软件包CHEMKIN结合,实现了化学反应与流动的耦合计算,对微型HCCI自由活塞发动机单次冲击的整个工作过程进行了数值模拟。通过完全理想条件下的工作过程模型进行了变参数研究,获得了不同冲程、不同初始当量比、不同压缩比(即自由活塞初始速度)情况下,着火时刻特性以及燃烧特性变化规律,为进一步获得控制燃烧过程的因素提供了理论依据;通过加入传热模型和漏气模型分别研究了传热和漏气对微型HCCI自由活塞发动机整个单次冲击工作过程的影响,得出了传热对微HCCI自由活塞发动机整个工作过程影响相对较小,而漏气对整个工作过程具有较大影响的结论。本文详细研究了微自由活塞发动机的工作过程中燃烧规律,以及微发动机的动力性能,为进一步开发该微型动力装置提供了理论依据。更多还原

【Abstract】 The structure of free-Piston Engine is simple, which is better suited to the development for micro.The method combinated HCCI with micro free-piston engine can not only avoid flame-quenching near the combustion chamber wall, but also solve the problem of ignition control of HCCI at the same time.Moreover, the efficiency of the energry of micro free-piston engine conversing to power is high. Therefore, the research based on HCCI combustion micro-free piston engine is expected to exceed restrictions by the smaller Combustor, and impact on the development of Power-Micro Electro Mechanical greatly.For the work characteristics of the micro HCCI free-piston engine, the two-dimensional models of the engine combustion under ideal conditions (adiabatic, no leakage), and considering the influnence of leakage and heat transfer respectively are established. According to relationship between the pressure on the piston and its velocity, the moving mesh procedures for simulating the piston work process are established to achieve the coupling gas chemical kinetics with the kinematics of piston. In this paper, the auther make use of the means of the chemical reaction coupled with the flow computing to model the whole working process of the HCCI free-piston engine single shot, using the software of STAR/Kinetics. The paper used the method of varying the influencing parameters to obtain the change of igniting time and combustion characteristic under the conditions of different stroke, different initial equivalence ratio, different compression ratio (initial piston velocities), further more, the paper provided the theory for controlling the combustion process. The influence of heat transfer and Leakage for the micro HCCI free-piston engine single shot process is researched respectively by the model contained the leakage or heat transfer, and got the conclusions that heat transfer impact on the entire operation process relatively small,and the influence of leakage is relatively larger.Finally, the paper studies the combustion characteristic in the micro HCCI free-piston engine operation process and the micro-engine dynamic performance, providing the theory for developmenting the micro-Power device.更多还原