EVALUATION OF FUEL SPRAY ATOMIZATION MODELS FOR CONDITIONS APPLICABLE TO LARGE MARINE DIESEL ENGINES

Due to the large size of marine diesel engines (an order of magnitude larger than automotive ones) it is expected that the physics of spray atomization, namely the primary and secondary breakup mechanisms, may differ from those encountered in the smaller automotive engines. Typically, diesel sprays in small engines disintegrate according to the shear and catastrophic breakup mechanisms. It is expected that, due to larger droplet sizes, injection velocities, and cylinder pressure, the catastrophic breakup mechanism will prevail in large marine diesel engines. The significant differences in the controlling non-dimensional parameters (Reynolds and Weber numbers) suggest that an evaluation of currently available atomization models for the conditions of large marine engines is necessary. In this work, we perform a preliminary evaluation of the most commonly used Lagrangian models for diesel sprays, namely the KH-RT, and E-TAB models, as well as the recently developed Unified Spray Breakup (USB) model. The problem setup consists of a constant-volume vessel, in which fuel injection is simulated with a KIVA-based CFD code. Here, tip penetration and breakup mechanisms are reported and compared for the three models of interest. Insight from experimental measurements is used to evaluate the computational results. Paper ID ILASS08-P-14