The Reduction of Soot Emissions by the Use of a Piston with Micro-Chambers on a Medium Duty Diesel Engine

The performance and emissions of a medium duty, turbocharged and aftercooled diesel engine fitted with both standard pistons and experimental pistons have been compared. The experimental pistons incorporated micro-chambers equi-spaced around the periphery of the bowl, connected to the bowl by drilled passages.

The tests were run using an “A-B-A” design at three engine speeds over the load range. The paper will report that the experimental pistons have a potential for significant soot reduction without an increase in NOx emissions and with similar fuel consumption.

Based on an analysis of the jet flow into and out of the micro-chambers, a possible mechanism for the soot reduction is proposed. The mechanism has been investigated further using VECTIS computational fluid dynamics (CFD) analysis.