Abstract
In a spark-ignition engine with intake port fuel injection, fuel is sprayed into the intake port under flow conditions and atomized droplets flow into the cylinder, some of which adhere to the intake port wall and form a liquid film. The liquid film adhered to the intake port is a factor in combustion fluctuations due to cycle-to-cycle variations of the air-fuel mixture in the cylinder, as well as unburned hydrocarbons and soot emissions. In this study, a wind tunnel experimental apparatus simulated an intake port was constructed to understand the wall adhesion characteristics of fuel spray in the intake port during engine startup and cold startup conditions. Scattered light photography was used to observe fuel spray characteristics in static and flow conditions, and total internal reflection laser-induced fluorescence (TIR-LIF) was applied to analyze the wall adhesion characteristics of fuel sprays. As a result, in the static field, the spray interaction increased with increasing injection pressure, and the amount of wall adhesion increased. However, in a flow field, the spray follows the flow as the injection pressure increases, and the amount of adhesion decreases.
