ID 41

Calibration of the KH-RT Model Constants on Predicting Evaporating Diesel Sprays

 

Abstract:

The KH-RT breakup model is widely used in high-pressure diesel spray simulations. This model involves six adjustable constants so that even for a sophisticated modeler, it is a time-consuming work to determine the model constants to achieve a successful simulation, particularly for evaporating sprays. This paper aims at providing the model calibration strategy for both liquid and vapor phase penetrations in high-pressure evaporating diesel sprays. The experimental data for calibrating the model is obtained from fuel injections with the injection pressure of 120 MPa, ambient temperature of 900 K and ambient density of 15 kg/m^3 in a high-temperature high-pressure constant-volume vessel. To evaluate the sensitivity of each model constant, numerical experiments are implemented with a commercial CFD (computed fluid dynamics) code and the BBD (Box-Behnken design) method. The results show that the breakup time constant in the KH-RT model plays a dominant role in predicting the evaporating spray. Although good agreement of the vapor phase penetration between the experimental and calculated results can be obtained with some combination of the model constants, unacceptable deviation of the simulation from the experimental data may be incurred for the liquid phase penetration. This implies that only calibration of non-evaporating sprays at room temperature is insufficient for a successful simulation of diesel spray combustion process. Finally, an optimized combination of the KH-RT model constants obtained by the BBD analysis is presented for evaporating diesel spray simulations. These findings are valuable for engineers and researchers who are considering diesel spray simulation with the KH-RT model.