Combustion performance and fuel injection timing adaptability of a lateral swirl combustion system for direct injection diesel engines

Abstract

To further study the combustion performance and injection timing sensitivity, the lateral swirl combustion system (LSCS) performance was compared against a widely-used TCD combustion system (TCDCS) experimentally in a single-cylinder diesel engine. The experimental results show the LSCS exhibited better combustion performance and lower emissions compared to the TCDCS: the fuel consumption and soot emissions were decreased by 2.5–4.2 g/kW∙h and 0.27–0.73 FSN at different speeds. Further, when the injection timing was retarded from −15 to −8°CA ATDC, the fuel consumption and soot emissions for the LSCS increased by 1.4% and 2%; while for the TCDCS these increases were 2.8% and 17%, respectively. Clearly, the fuel consumption and soot emissions for the LSCS increase relatively slowly. Then, simulation was created to reveal the wall-flow-guided mechanism. For the LSCS, the wall-flow-guided geometry is a vertical convex edge, which is different from a traditional circular ridge: the spay jet almost invariably collides on the convex edge to form the wall-flow-guided and interferential interactions, promoting fuel-air mixing and exerting excellent injection timing adaptability. Therefore, the LSCS exhibits better combustion performance, and appropriately delaying the injection timing can simultaneously obtain relatively better the fuel consumption and soot and NOx emissions.