Investigation of Breakup Modeling of a Diesel Spray by Making Comparisons with 2D Measurement Data

In this study, the characteristics of diesel spray droplets, such as the velocity and the diameter were simultaneously measured by using an improved ILIDS (Interferometric Laser Imaging for Droplet Sizing) method on a 2D plane to evaluate the droplet breakup modeling. In numerical analysis, DDM (Discrete Droplet Model) was employed with sub-models such as droplet breakup, droplet drag force and turbulence. Experiments have been performed with an accumulator type unit-injector system and a constant-volume high-pressure vessel under the condition of quiescent ambient gas. The injection pressure and ambient gas pressure were set up to 100 MPa and 0.1 / 1 MPa, respectively. The nozzle orifice diameter was 0.244 mm with a single hole. The measurement region was chosen at 40 ∼ 60 mm from the nozzle-tip. Numerical analysis of diesel sprays was conducted and the results were compared to the measured results. A modification of TAB droplet breakup model was made by introducing statistically determined breakup time. As a result, the profile of droplet diameter distribution could be well predicted even in strongly unsteady regions compared to experimental results. Also, spray predictions under an engine-like condition were carried out. A plausible result was deduced using the modified breakup model compared to of the original breakup model.