Coupled 1-D/3-D Analysis of Fuel Injection and Diesel Engine Combustion

One of the most critical elements in diesel engine design is the selection and matching of the fuel injection system. The injection largely controls the combustion process, and with it also a wide range of related issues, such as: fuel efficiency, emissions, startability, load acceptance (acceleration) and combustion noise. Simulation has been a valuable tool for the engine design engineer to predict and optimize key parameters of the fuel injection system. This is a problem that spans a number of subsystems. Historically, simulations of these subsystems (hydraulics, gas dynamics, engine performance and 3-D CFD cylinder modeling) have typically been done in isolation. Recently, a simulation tool has been developed, which models the different subsystems in an integrated manner. This simulation tool combines a 1-D simulation tool for modeling of hydraulic and gas dynamics systems, with 3-D CFD code for modeling the in-cylinder combustion and emissions. This required the development of specialized methodology to handle the differing time scales between hydraulics and gas dynamics, and also the 3-D computations of atomization and combustion in the cylinder. The results of transient simulations and optimization simulations in the integrated systems are discussed.