Complex injection strategies for hydrogen-fueled HCCI engines

Mixture formation methods can have a significant impact on the performance and reliability of homogeneous charge compression ignition (HCCI) engines fueled by hydrogen. This paper investigates the ability of fuel injection strategies based on multiple-pulse direct injection (DI) as well as combinations of port fuel injection (PFI) and direct injection to prepare an ideal in-cylinder hydrogen–air mixture and control the autoignition process. Computations are performed using the one-dimensional turbulence (ODT) model formulated for engine simulations. It is found that multiple DI and hybrid PFI/DI schemes can be used for varying load requirements that could lead to an extension of the operating range of HCCI engines. A combination of volumetric autoignition and localized high-temperature burning are found to occur.