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The purpose of this study is to develop a modeling and simulation environment for the early design and testing for high pressure injection of alternative fuels in a medium-speed engine application. The proper injection of fuel into the cylinder at the correct timing and with the desired rate is a key to high combustion efficiency. The fuel spray and gas jet characteristics are governed by the injection pressure and nozzle geometry. Incorrect injection causes a reduced efficiency and increasing concentration of harmful emissions. In addition to efficient and clean combustion, safety issues are also important design features for fuel injection systems. In particular, the handling of volatile alternative fuels such as natural gas requires special safety functions to prevent hazardous incidents.

In internal combustion engines, fuel injection timing, injection rate and pressure is optimized to ensure suitable combustion and reduce emissions. Injectors are complex systems where mechanical, electromagnetic, and fluid dynamics interact together. Numerical model development of injectors allows for investigating different conditions, as well as optimization of the system in a safe manner. In this study, a 1-dimensional (1D) mathematical model of a direct gasoline injector (GDI) is presented, supported by computational fluid dynamics (CFD) in-nozzle flow simulations. The described system is a commercially available injector where the internal geometry was captured using silicone molds of the nozzle. The model includes the representation and interaction of the different components across several domains using the bond graph methodology. In the injector, the needle is magnetic and is lifted when an electromagnetic field is activated.