Integrated Computational Study for Total Atomization Process of Primary Breakup to Spray Droplet Formation in Injector Nozzle

The advanced development and optimization of fuel atomization in port and direct injection systems for automobile engine is desired for the improvement of fuel combustion performance and thermal efficiency of the engine. Computational prediction and design of injector nozzle spray flow is an effective method for that. However, a practical simulation method of the continuous primary, secondary spray breakups and the spraying behavior have not been developed yet. In this study, we have developed the integrated computational method of the total fuel atomization process of the injector nozzle. This new computational approach is taking into account the nozzle internal flow to form the primary breakup using Volume of Fluid (VOF) method in connection with the spray flow characteristics to the engine cylinder using Discrete Droplet Model (DDM). The flow field data of fuel velocity, turbulent energy and dissipation rate obtained by Eulerian approach (VOF) are transferred to Lagrangian process (DDM) as the initial numerical conditions of the droplet velocity, diameter and flow rate. For flow field data acquisition to transfer process (VOF to DDM), we have newly developed the coupler software named VOF-DDM Bridge Tool (VDBT). The presented numerical method is available to predict the fuel spray angle, the particle size distribution and the behavior of the spray penetration in total atomization and spray process. Furthermore, we confirmed that the obtained numerical results shows reasonably agreement with the optical spray measurement results.