Development of a computing procedure for the sequential atomization process of a multiaperture injector and a swirl injector

The development and optimization of fuel atomization in the port-injection and direct-injection systems of automobile engines are important in terms of improving the fuel combustion performance and thermal efficiency of engines. An effective method of achieving this goal is computational prediction. An integrated computational method for the total fuel atomization process of the injector nozzle was developed. This new computational approach considers the nozzle internal flow using the volume of fluid (VOF) method and the spray flow to the engine cylinder using the discrete droplet model (DDM). Also, a coupling code called the VOF-DDM bridge tool to transfer the flow-field data obtained using the VOF method to the initial numerical conditions of the DDM was developed. In the VOF-DDM bridge tool, the initial diameters for liquid breakups from a liquid column and a liquid sheet were evaluated using different methods. The proposed method was applied to spray flows from hole injector and swirl injector systems. The experiments of the spray flow from hole and swirl injectors were carried out to assess the validity of the proposed numerical simulation. The present numerical method predicted the spray behavior for relatively low fuel pressure and the qualitative behavior for hole injector systems, such as the increase in spray tip penetration with increasing fuel pressure. However, the method encounters problems at high fuel pressure. In the simulation of a swirl injector, the predicted spray tip penetration and spray angle agree reasonably with corresponding experimental results.