Ducted fuel injection: Numerical study of soot formation and oxidation using detailed soot modeling approach in a compression ignition engine at different loads

The ducted fuel injection strategy is an innovative method that significantly prevents soot formation in direct injection compression ignition engines. This method is based on the injection of the fuel directly into the combustion chamber through the tube placed in front of the injector hole. The fuel mixes with air inside the duct before ignition. Thus, the formation of soot can be prevented by reducing the local equivalence ratio in the lift-off length in the combustion chamber. In this study, the implementation of the duct geometry to the compression ignition engine was evaluated in-cylinder flow and emission formation. The duct geometry was adopted for the test engine. The effects of the ducted fuel injection (DFI) on the combustion and performance of a compression ignition diesel engine were investigated. Conventional diesel combustion (CDC) and DFI system at low (25%), medium (50%), and high (75%) loads were compared in terms of performance, combustion, and emission using an experimentally validated engine model. Particle size mimic (PSM) detailed soot mechanism was used in the CFD model in order to solve the complex soot formation and oxidation with detailed chemistry. Compared to CDC, the DFI method reduces soot emissions up to 67%. In addition, the DFI strategy decreases CO and HC emissions up to 39% and 26%, respectively. With this innovative method, it has been observed that exhaust emissions are reduced without compromising engine performance.