Combustion performance characteristics of double-layer diverging combustion chamber compared with re-entrant chamber and omega chamber

Abstract

Combustion chamber is a main component for Diesel, as it organizes the fuel-air mixing and combustion processes and eventually determines Diesel performance. In the past decades, the chamber turned into the higher radius-to-depth ratio and lower area-to-volume ratio type to increase the in-cylinder air utilization and promote the fuel spray spreading. The Double-Layer Diverging Combustion chamber (DLDC chamber) was designed in this background. In order to obtain the DLDC chamber performance characteristics comprehensively, a 135-type Diesel with a DLDC chamber, a re-entrant chamber and a ω chamber was selected. The results suggested that the DLDC chamber decreased the BSFC and soot emission, but increased the NO_x with higher p_max and heat release rates during the premixed combustion phase, as it could divide the fuel into two layers and promote the fuel spreading and combustion; adjusting the injection parameters made the BSFC and exhaust emissions of the DLDC chamber change quite differently, because the different layers of the DLDC chamber had their own chamber-spray-charge motion matchings. Finally, the investigation indicated that the DLDC chamber provided lower exhaust emissions compared with the other two chambers by keeping the same fuel consumption; moreover, the DLDC chamber provided the lowest BSFC and soot emission in the three chambers under the same NO_x emissions level.