Modelling of Diesel spray dynamics and comparison with experiments

The capabilities of the Taylor analogy breakup (TAB) and wave breakup (WB) spray models, already existing in the literature, were evaluated in KIVA-II code. Also, a novel droplet deformation and breakup (DDB) model that takes into account the nonlinear effects which manifest at large deformation of the drops was incorporated and tested in KIVA-II. The assessment of the three models was performed by using experimental measurements of tip penetration, spray cone angle and Sauter mean radius (SMR) in a cylinder optically accessible closed vessel at room temperature and high gas density. High speed photography and laser light extinction techniques were simultaneously used to detect data along a n-heptane jet coming out from a single hole nozzle of 0.20 mm diameter supplied by PE- Bosch injection pump operating in single shot by electro- hydraulic device. The KIVA calculations with TAB model in terms of penetration and SMR do not predict accurately the experiments. The WB and DDB models match well the experimental penetration data at low temperature and, at high temperature, the DDB model shows the highest penetration rate suggesting that it is more appropriate for simulating the spray dynamics for small engine like conditions in which the distance between the nozzle tip and the combustion chamber wall is very low.