Abstract
In order to reduce particulate matter emitted from gasoline direct injection spark ignition engine, it is important to reduce the fuel film deposition on the wall and local rich air-fuel mixture formation. As a means to reduce these, the high pressure fuel injection is considered to be effective. In this study, we evaluated the influence of increasing fuel injection pressure to the spray behavior under the high-temperature and high-pressure ambient assuming the practical combustion chamber in engines. The air entrainment flow velocity into the spray was measured by using consecutive Particle Tracking Velocimetry (PTV) method with a high-speed camera and a high-frequency Nd:YAG laser. And, fuel vapor phase was measured by using Laser Induced Exciplex Fluorescence (LIEF) method with a constant volume vessel. The air entrainment flow velocity into the spray was increased with time after injection, and it became fast by increasing the pressure. The area of fuel film deposition was decreased, and the rate of the film vaporization was increased. The height of vapor phase around the spray tip rose by increasing the fuel pressure.
