Numerical Study of Liquid Fuel Spray Characteristics

The modified drop drag (MDD) model was further improved and implemented in the KIVA code for better describing the liquid fuel spray characteristics in diesel engine combustion chambers. The MDD model accounts for the effects of both the drop's frontal area and its drag coefficient as a function of its distortion on drop drag and drop breakup. The new version of the KIVA code with the MDD model was tested for the cases of the free liquid spray and the spray/wall impingement on a solid wall from single-hole fuel injection nozzles in high pressure chambers at room temperature condition. The results from numerical calculation by using the new version of KIVA code with the MDD model and the experimental data were in good agreement for both the free liquid spray and the spray/wall impingement cases. In addition, in the spray/wall impingement case the effect of the MDD model was seen to be very important on both the spray penetration and the wall spray height after impingement. In contrast to earlier models, it was found that the calculated data were insensitive to the choice of the breakup time constant, B1, after impingement. This indicates that the physics of drop destabilization processes following wall impingement are accounted for more reasonably with the MDD model.