The use of Ducted Fuel Injection (DFI) for attenuating soot formation throughout mixing-controlled diesel combustion has been demonstrated impressively effective both experimentally and numerically. However, the last research studies have highlighted the need for tailored engine calibration and duct geometry optimization for the full exploitation of the technology potential. Nevertheless, the research gap on the response of DFI combustion to the main engine operating parameters has still to be fully covered.
Previous research analysis has been focused on numerical soot-targeted duct geometry optimization in constant-volume vessel conditions. Starting from the optimized duct design, the herein study aims to analyze the influence of several engine operating parameters (i.e. rail pressure, air density, oxygen concentration) on DFI combustion, having free spray results as a reference.
Furthermore, the duct wall temperature influence is investigated in order to preliminary explore the needs in terms of duct thermal management.
The impact of the above-mentioned parameters on combustion and emissions formation processes is assessed, highlighting the soot mitigation mechanisms enabled by DFI operation.
The optimized duct design led to a strong soot reduction for most of the operating conditions tested, thus confirming the robustness of the proposed geometry. This preliminary understanding step via numerical simulation of DFI calibration requirements paves the way to future studies on duct-equipped engine applications.