Effect of baffles in the combustion chamber of a gasoline direct injection engine – A computational fluid dynamics analysis

In-cylinder flows significantly impact the performance and emissions of internal combustion engines. Tumble, swirl, and squish flows enhance turbulence, improving air-fuel mixing, combustion efficiency, and emission reduction. Various techniques are employed to induce these flows, including modifying piston top profiles, valve shrouding, masking, and utilising directed and helical ports and vanes in ports. However, research on modifying engine cylinder heads is limited in the literature, often due to space constraints. This study proposes the use of baffles within the cylinder head to enhance engine performance without significantly affecting the combustion chamber space, employing computational fluid dynamics (CFD) analysis. The engine operates at 1000 rev/min under part-load conditions with a fixed compression ratio of 10 for the analysis. A novel discretisation scheme is implemented to assess the spatial distribution of the in-cylinder air-fuel mixture. Results indicate that the presence of baffles facilitates effective mixture stratification, even during early-stage fuel injection. Furthermore, this enhancement leads to a 4 % increase in indicated mean effective pressure and a 9 % in indicated thermal efficiency. Notably, hydrocarbon emissions are reduced by approximately 85 %, while carbon monoxide emissions decrease by about 38.5 %.