Computational investigation of diesel combustion and soot formation with a phenomenological soot model under different temperatures in a constant volume chamber

The previous nine-step phenomenological soot model was revised by including the oxidation effect on soot number density. Using KIVA-3V Release 2 code coupled with this revised phenomenological soot model, multi-dimensional computational fluid dynamics (CFD) simulations of diesel spray combustion in a constant volume chamber was conducted to investigate the combustion physics and soot emission characteristics. Meanwhile, experiments were conducted in an optical constant volume combustion chamber under different ambient temperatures (800, 900, 1000 K), from which the combustion characteristics and soot distributions were obtained for validation. The results indicate that ignition retards with the decrease of ambient temperature, which results in more air-fuel mixing controlled diffusion combustion at high ambient temperature, and more premixed combustion at low ambient temperature. The corresponding soot formation and distribution shows that the soot emission is strongly related to the local equivalence ratio, which leads to lower soot emission in the lower initial temperature case with more homogeneous mixture. Compared to previous nine-step model, the revised model predicted lower soot number and bigger soot particles size.