压燃式自由活塞直线发电机工作过程数值仿真

为研究压燃式自由活塞直线发电机的动力学特性,对其启动和稳态工作过程进行了数值仿真计算,并对自由活塞直线发电机的负荷特性和频率特性进行了分析.结果表明,与曲柄连杆式发动机相比,自由活塞发动机在其上止点附近有非常大的加速度,使得在上止点附近压缩行程较慢和膨胀行程较快.随着系统输出功率的提高,自由活塞发动机的缸内峰值压力、压缩比及指示效率不断下降;而直线电机载荷系数、峰值电磁力及循环加入能量不断增加.随着系统的运转频率不断提高,直线电机的载荷系数不断降低,最大峰值电磁力将在中间某一工作频率取得;而活塞平均速度、自由活塞发动机的指示效率和系统输出功率不断增加.

Working Process Numerical Simulation of Compression Ignition Free-Piston Linear Alternator

To analyze its dynamic characteristics, the starting process and stable operation of a compression ignition free-piston linear alternator (FPLA) were simulated with numerical methods, and the load and frequency characteristics of FPLA were analyzed. The results indicate that, compared with crankshaft-driven engine, free-piston engine (FPE) has greater acceleration around its top dead center, which leads to slower compression stroke and faster expansion stroke. With the increasing of power output of FPLA, the in-cylinder peak pressure, compression ratio and indicated efficiency keep decreasing, while the load coefficient of linear alternator, peak electromagnetic force and energy input every cycle keep increasing. With the increasing of operating frequency, the load coefficient of linear alternator keeps decreasing while the averaged piston speed, indicated efficiency and power output keep increasing, and the maximum electromagnetic force is reached at certain frequency in between.