Optimizing Exhaust Port in 2-stroke Free Piston Engine for Improving Scavenging Efficiency using CFD

This paper discusses the influence of exhaust port shape in-cylinder gas dynamics of a2-stroke spark ignition free piston engine(FPE) model via computational fluid dynamic(CFD) for improving the scavenging performance on. The objective of the work wasto optimize the contour of exhaust port for higher scavenging efficiency and low short circuiting of fresh charge admitted into the engine. virtual analyses were carried out using ANSYS-FLUENT by selecting and varying the two-stroke free piston engine parameters namely exhaust port shape, exhaust port height, piston linear velocity and combustion pressure. The CFD analysis reveals that the scavenging efficiency was increased to 86.51% with 0.23 short circuiting for the free piston engine having elliptical shaped exhaust port (port height decreased 2mm from BDC)compared to the square shaped exhaust port yielding 87.62% scavenging efficiency with 0.38 short circuiting mass fraction of fresh charge.