Investigation of temperature effect on soot formation on the basis of CFD coupling with phenomenological soot model

On the basis of nine-step phenomenological soot model, the surface oxidation influence on soot number density was considered for four operating conditions. The revised phenomenological soot model was implemented into KIVA-3V Release 2 code, with which multi-dimensional computational fluid dynamics simulations were conducted to investigate the combustion characteristics and soot behavior of diesel spray combustion in a constant volume chamber, at different initial temperatures(800, 900, 1000 K). Meanwhile, experiments were conducted under the same conditions to validate the model. Results indicate that ignition delay increases while combustion duration decreases with the decrease of ambient temperature, indicating the transition of combustion type from diffusion combustion to premixed combustion. Under lower ambient temperature, both soot formation and oxidation mechanism were suppressed, while local peak temperature and high temperature regions do not obviously decay. However, the area of local fuel-rich region shrank dramatically, directly causing the reduction of soot emission at low ambient temperature.