An Numerical Investigation into the Dynamic and Thermodynamic Characteristics of a Two-Stroke Free Piston Linear Engine

The dynamic and thermodynamic characteristic of a two-stroke free piston linear engine was simulated based on the combination of three mathematical models including dynamic, linear alternator and thermodynamic model. The dynamic model consists of an analysis of force balance equation and the motion equations of piston in the cylinder. The linear alternator model consists of an analysis of electrical load which is considered as a resistant force for the motion of piston. The thermodynamic model was used to analysis thermodynamic processes occurred in the engine cycle including scavenging, compression, combustion and expansion. In order to provide information for the investigation, effect of spark timing and spring stiffness was analyzed. The results are divided by two parts including motoring mode and firing mode. In which, the initial parameters are calibrated by comparing to experimental data at motoring mode. For firing mode, the simulation results show that by increasing spark timing and spring stiffness, the performance of free piston linear engine was improved.