Improving the Accuracy of 1-D Fuel Injection Modeling

In this study, one-dimensional fluid dynamics simulation software was utilized in producing common rail diesel fuel injection for varying injection parameters with enhanced accuracy. Injection modeling refinement is motivated by improved comprehension of the effects of various physical phenomena within the injector. In addition, refined injection results yield boundary conditions for three-dimensional CFD simulations. The criteria for successful simulation results were evaluated upon experimental test run data that have been reliably obtained, primarily total injected mass per cycle. A common rail diesel fuel delivery system and its core mechanics were presented. System factors most critical to fuel delivery were focalized. Models of two solenoid-type common rail injectors of different physical sizes and applications were enhanced. The simulation models utilized measured cylinder pressure data and other basic operating parameters in their functions as references and boundary conditions. Injector manufacturer data were employed as a tool in simulation model build-up, as well as evaluation of several functional characteristics of common rail injectors. A model for the discharge coefficient of nozzle orifices that accounts for laminar, turbulent and cavitational flow was implemented. Injector needle dynamics were tuned by examining injector control valve flow with the inclusion of a tuning parameter. In addition to experiments, results were compared with earlier simulation efforts. Improvement in total injected mass accuracy was perceived with the new simulation model. Produced injection delays were compared. Qualitative alterations in injection mass flow profiles were found. Control valve flow tuning was deemed highly sensitive in result formation. Nozzle orifice flow model parameters were considered useful for model fine-tuning.