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 NOx with higher pmax 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 NOx emissions level.
Taking the two chambers of swirl chamber indirect injection diesel engine (SC engine) as two relative but independent thermodynamic systems, this paper builds up thermodynamic equations respectively in the two chambers, together with the mass and enthalpy $ow equations describing the mass and energy exchanges between them. This model, based on the synchronous pressure diagrams measured in the two chambers, is used to calculate the thermodynamic state of medium and heat-release process in both of the chambers. Furthermore, with the help of the thermodynamic equivalent system, the calculation of the variable $ow coeficient of the connecting passage has been successfully achieved. A Model 6105Q SC engine is taken as a practical calculation example to reveal the Combustion pattern of this type of engine. In the last part of this paper, several methods currently used for the heat-release rate calculation have been analysed to show their application field and accuracy.
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