Numerical Investigation of the Effect of Piston Geometry on the Performance of a Ducted Fuel Injection Engine

Ducted Fuel Injection (DFI) engines have emerged as a promising technology in the pursuit of a clean and efficient combustion process. This article aims at elucidating the effect of piston geometry on the engine performance and emissions of a metal DFI engine. Three different types of pistons were investigated and the main piston design features including the piston bowl diameter, piston bowl slope angle, duct angle and the injection nozzle position were examined. To achieve the target, computational fluid dynamics (CFD) simulations were conducted coupled to a reduced chemical kinetics mechanism. Extensive validations were performed against the measured data from a conventional diesel engine. To calibrate the soot model, genetic algorithm and machine learning methods were utilized. The simulation results highlight the pivotal role played by piston bowl diameter and fuel injection angle in controlling soot emissions of a DFI engine. An increase in piston bowl diameter increases the room for spray penetration, promoting fuel-air mixing and subsequently reducing soot formation. Furthermore, variations in the fuel injection angle significantly influence the distribution of fuel within the combustion chamber, impacting ignition, combustion efficiency and soot emissions. The study highlights how DFI engines benefit largely from altered piston shapes compared to conventional diesel engines. Optimized piston geometries have been identified that not only minimize soot emissions but also enhance overall engine performance. These findings are crucial in the context of meeting stringent emissions regulations while maintaining or improving fuel economy, a critical objective for engine manufacturers. The proposed optimized piston geometries represent a promising avenue for enhancing the environmental and economic sustainability of DFI engines, paving the way for cleaner and more fuel-efficient engines in the future.