A transient computational fluid dynamic model of a unit injector using methanol fuel [electronic resource] /

by McKenzie, E. A.

The use of alternative fuels such as Ethanol, Methanol and Natural Gas in automotive applications has increased due to the strict environmental regulations. These are used to reduce automotive emissions, especially in heavy trucks and city bus fleets. Most of these vehicles use diesel fuel as their primary fuel. Trucks and buses with Detroit Diesel engines have the option to operate using methanol as their primary fuel instead of diesel fuel. Due to the low lubricity of methanol fuel, the unit fuel injectors injecting methanol fuel have a shorter operating life than those injecting diesel fuel do. To study the fluid flow effects of methanol undergoing the injection process, experimental data was obtained for a unit injector using methanol fuel. The applied force for injection was measured and the resulting internal chamber pressure was measured along with the flow rate. The measured applied force was found to be 35% greater using methanol fuel than it was using diesel fuel. Friction between the injector piston and the barrel wall is the cause for the excess force. Using the computational fluid dynamics programs FLUENT and FLUENT/UNS obtained the pressure and velocity profiles for pre-selected locations in the fluid path of the injector. Locations of high and low velocity areas were determined to be performance inhibitors and possible failure points. ii