Effect of Piston Shape on Scavenging in a Two-Stroke Engine - A CFD Analysis

This study focuses on effect of piston shape on in-cylinder flows in a conventional loop scavenged two-stroke engine using CFD. Three piston-shapes viz., flat, flat with center-bowl and flat with center-dome are analyzed along with standard piston. The CFD solution has been obtained by using commercial code STAR-CD. First the CFD results are compared with those of experimental values obtained from particle image velocimetry (PIV). For comparison among various piston shapes, various parameters viz., velocity vector plots, tumble ratio (TR), turbulent kinetic energy (TKE) at various crank angles are used. Scavenging and trapping efficiencies are also calculated for each piston configuration. From the results, it is found that flat with center-bowl piston is the best in terms of in-cylinder flow characteristics. It gives higher TR and TKE with very little effect on efficiencies.