Abstract
The aim of this study is to elucidate effects of atmosphere pressure in combustion chambers, fuel injection pressure and injection hole number on exhaust characteristics from diesel combustion. 2-color radiometry thermal imaging system with a high speed digital camera was used to measure flame evolutions in the combustion chamber of a rapid compression machine. The atmosphere pressure was raised up to 8 MPa to simulate supercharging conditions. An increase in the number of injection hole increases the NOx concentration of exhaust gas through the flame area enlargement. As the atmosphere pressure rises, the combustion period is elongated due to the decrease in the amount of mixture formed before ignition, which leads to the slight increase in EINOx. The injection pressure rise locally enhances the NOx production in expanded high temperature regions while suppressing the total NOx production through the short residence time of the flame. The difference between EINOx with different injection pressures is therefore quite small.
