Computational Analysis of Peripheral Fuel Injection to Enhance Fuel–Oxidizer Mixing in the Near-Field of Diesel Sprays

Abstract Recently, we have introduced peripheral fuel injection (PeFI) for diesel engines whereby fuel is injected at an angle from the periphery of the cylinder head using multiple single-hole injectors. PeFI has been developed to obtain free flames away from the surfaces to minimize heat loss and to reduce emissions by increasing access to the oxidizer both in the near-field of the injector and in the downstream diffusion flame. In this study, three-dimensional (3D) computational fluid dynamics (CFD) analysis is utilized to investigate fuel–air mixing in the near-field of diesel sprays with the goal to compare conventional diesel combustion (CDC) and PeFI strategies. The study utilizes experimentally determined rate of injection (ROI) profiles for multihole and single-hole injectors to replicate published data for nonevaporating CDC and PeFI sprays acquired in a pressurized constant volume test chamber. The CFD model thus validated is extended to investigate fuel–air mixing in an evaporating spray at ECN Spray A reference conditions of ambient pressure and temperature. Results show significant differences in the flow field in and around the fuel jet and within the chamber for CDC and PeFI strategies. PeFI case with its faster initial ROI ramp-up increases initial mixing and achieves faster fuel vaporization compared to those for CDC case. Quantitative analysis reveals that PeFI case provides 20–40% increase in oxidizer entrainment rate at quasi-steady conditions compared to that for CDC case.