二冲程自由活塞发动机扫气与排放仿真研究
张宇1，肖进1*，张宸2
1.上海交通大学动力机械与工程教育部重点实验室,上海 200240；2.上海交通大学智慧能源创新学院,上海 200240
摘要：利用CONVERGE软件建立二冲程自由活塞发动机的三维计算流体动力学(computational fluid dynamics, CFD)仿真模型，研究扫气压力、点火时刻对缸内扫气、燃烧和CO2、NOx、CO废气排放的影响。仿真研究结果表明：随着扫气压力增大，缸内扫气效果变好，更多新鲜气体进入缸内，CO2和NOx的生成和排放增加，CO减少；点火时刻影响缸内燃烧，随着点火时刻推迟，缸压峰值和缸内平均温度降低，CO的生成及排放增加，NOx的生成及排放减少。自由活塞发动机试验过程时，应当综合选取工况条件，使得燃烧、扫气、排放等达到综合最优效果。
关键词：自由活塞发动机；二冲程；扫气；换气；燃烧；排放；三维CFD仿真
Simulation study on scavenging and emission of two stroke free piston
engine
ZHANG Yu1，XIAO Jin1*，ZHANG Chen2
1. Key laboratory for Power Machinery and Engineering of the Ministry of
Education，Shanghai Jiao Tong
University, Shanghai 200240, China；
2. College of smart energy, Shanghai Jiao Tong University, Shanghai 200240,
China
Abstract：A CFD simulation model of a two-stroke free piston
engine is established by CONVERGE software. The effects of scavenging pressure,
ignition time on in-cylinder scavenging, combustion and exhaust emissions (CO2,
NOx, CO) are studied. The results show that with the increase of scavenging
pressure, the scavenging effect in the cylinder becomes better, more fresh gas
enters the cylinder, the emission of CO2 and NOx increase, and CO decreases.
The ignition time affects the combustion in the cylinder,with the delay of
ignition time, the peak cylinder pressure and the average temperature in the
cylinder decrease, the emission of CO increases, and NOx decreases. In the
process of free piston engine test, the operating conditions should be
comprehensively selected to achieve the comprehensive optimal effect of
combustion, scavenging, emissions, etc.
Keywords:free piston engine; two stroke;
scavenging;ventilation; combustion;emission;3D CFD simulation
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