Effect of injection condition and swirl on D.I. diesel combustion in a transparent engine system

Abstract

The objective of this work was to investigate the effects of injection conditions and swirl on D.I. diesel combustion using a transparent engine system. The test engine is equipped with a common rail injection system to control injection conditions and to obtain split injection characteristics. A combustion analysis and steady flow test were conducted to measure the heat release rate due to cylinder pressure and the swirl ratio. In addition, spray and diffusion flame images were obtained using a high speed camera. The LII & LIS methods also used to obtain 2-D soot and droplet distributions. High injection pressure was found to shorten ignition delay, as well as to enhance peak pressure. The results also revealed that the heat release rate in the premixed combustion region was markedly reduced through the use of pilot injection, while the soot distribution and the heat release rate in the diffusion combustion region were increased. The swirl effect was found to shorten ignition delay at certain injection timings, and to enhance the heat release rate in all experimental conditions.