Diesel combustion analysis by two-zone model (1st Report, comparison between model analysis and experiment)

The proposed two-zone model consists of a burned zone and an unburned zone, in which the changing processes are thermodynamically independent except that the air is entrained from the unburned zone to the burned zone in accordance with the specified excess air ratio pattern during combustion. The excess air ratio of the diffusion combustion period is assumed to be constant in the present model. The calculated histories of the burned zone gas temperature and soot formation were compared with the measured time histories of the flame temperature and the KL value based on the infrared two-color method. The analytical results agree quantitatively or qualitatively with the experimental results, except for the prediction of the swirl effect. As a result, it was shown that the present two-zone model analysis is very useful and effective in evaluating the combustion process in a DI diesel engine.