Based on the study of single-cylinder compression ignition of the miniature free-piston power plant

combined with the single-impact combustion visualization test

the simplified models intake and exhaust port distance L

intake port angle α

exhaust port angle β

intake port diameter Din and exhaust port diameter Dout were used in the dual-cylinders research to perform numerical simulation calculations

making the entire operating conditions more stable and efficient. When the distance between intake and exhaust ports increases

the scavenging efficiency of air exchange process decreases gradually. At the same time

when the scavenging angle of the intake and exhaust ports becomes a certain angle

an airflow vortex is formed in the combustion chamber

which can improve the scavenging efficiency. When the intake and exhaust diameters continue to increase

the scavenging efficiency will increase first and then decrease

which further shows that the diameters have a significant impact on the scavenging process. The analysis shows that the optimal design size of the intake and exhaust structure are L=1 mm

α=30°

β=60°

Din=0.5 mm

and Dout=0.6mm. This design size has laid a theoretical foundation for studying the air exchange process of the two-cylinder micro free-piston engine.