微自由活塞发动机HCCI着火界限研究

开展微燃烧室里均质压缩燃烧(Homogeneous charge compression ignition，HCCI)可视化试验，进行定性分析，并以试验为基础建立三维数值模拟计算模型；基于丙烷燃烧化学反应动力学机理，提出自由活塞运动与燃烧过程耦合的计算方式，通过编写STAR-CD软件中的动网格子程序，对微燃烧室里均质气体压缩燃烧过程进行了数值模拟研究；分析了各种参数对微HCCI着火特性的影响，得出在理想模型下的压缩着火界限，即当量纲一参数压缩比不小于55时，均质气体总能压缩着火；并揭示泄漏对均质压缩燃烧过程的影响，得出在不同泄漏间隙尺寸下着火界限的变化情况，为微自由活塞发动机的设计提供一定的理论依据。

Study on Ignition Limit of HCCI in Micro Free-piston Engine

The visual experiment of homogeneous charge compression ignition (HCCI) in micro combustion chamber is carried out, some qualitative analysis is got, and multidimensional simulation model based on this experiment is built. Based on the propane combustion kinetics, the numerical calculation method for combustion process coupling with the free-piston movement is put forward, through editing the dynamic mesh subroutine in STAR-CD, the process of HCCI in the micro chamber is studied. The influence of various characteristics on micro HCCI is researched, and the compression ignition range in an ideal model is got, when the dimensionless parameter of compression ratio is not less than 55, the mixture can always be compressed ignition. The influence of gas leakage on combustion process and the variation of compression ignition limit under different leakage size are also revealed, all this research can be the basic theories for designing the micro free piston engine .