Research and development of double swirl combustion system for direct injection diesel engine

In order to decrease emission and fuel consumption of diesel engine, a new combustion system has been developed in the authors' laboratory. In this paper, main research achievements of the new combustion system DSCS (Double Swirl Combustion System) are introduced. The new spray and mixing mechanism from study of high-speed photography is described, and the influence of the main structure and matching parameters of DSCS on spray jet is also discussed including the formula description of the double swirl flow. Simulation results on the process of spray and combustion of DSCS showed that fuel jet collides with the ridge of DS combustion chamber and then splits into double swirls, and that the side near chamber centre of spray directly contacts more air. These cause reduction in mixing period of diffusion, more even distribution of spray and faster combustion. Comparative experiments of DSCS on single and multi-cylinder engines with original engines have shown that DSCS had many advantages on having ideal heat release rate, better fuel economy, lower emission and lower thermal load. Then, owning to the wide application of electronic-controlled fuel injection system on diesel engines, the developing potential and bright future of DSCS has been highlighted.