自由活塞初速度对微发动机燃烧特性的影响

Effect of initial velocity on combustion character in micro HCCI free-piston engine

根据自由活塞发动机的动力学特点,提出单次冲击微型均质充量压燃(HCCI)自由活塞发动机工作过程的模拟方法,并对目前定容燃烧模型进行一定的修正.考虑自由活塞的动能变化对燃烧参数的影响,提出自由活塞截断速度的概念,比较改进后的燃烧模型与目前的定容燃烧模型的计算结果,显示出改进模型的合理性.同时运用改进模型对HCCI自由活塞发动机不同初始速度下的燃烧特性进行模拟,得到了工作压力、温度、着火时刻的变化规律,以及自由活塞运动特性,为该微动力装置的设计提供了理论依据.

Based on the kinetic characteristic of free-piston engine, a method was proposed to simulate the operation of single-shot micro free-piston HCCI engine and a modified combustion model was built to simulate the combustion process. Considering the effects of kinetic energy of the free-piston on parameters of combustion process, a conception of cut-off velocity of the free piston has been put forward. The simulation result of the modified combustion model was compared with that of the original fixed-volume batch reactor model, and the comparison showed the rationality of the modified combustion model. At last, the combustion process in the micro free piston engine with different initial free piston velocities was simulated using the modified combustion model. The computational results provide design basis for the micro free piston engine.