Impact of Injector Geometry and Parcel Injection Location on Flash Boiling Spray Simulations of the ECN Spray G Injector

For fuels sprays under flash boiling conditions, the near nozzle region experiences rapid changes in ambient conditions due to the flashing liquid. So, it is crucial to understand the influence of spray boundary conditions on parcel-based simulations for improved predictions of fuel spray behavior in engine applications. This study builds upon previous research investigating the impact of detailed injector tip geometry on parcel simulations of non-flash boiling conditions by investigating how flash boiling behaviors affect the near nozzle region and parcel initialization conditions. Four key parameters were varied individually from a baseline spray simulation model, which resulted in a total of five cases. The parameter variations were the presence of detailed injector tip geometry versus a simplified flat surface, parcel initialization at the nozzle exit versus at the counterbore exit, the use of experimental rate-of-injection versus one-way coupling with an internal nozzle Volume of Fluid (VOF) simulation, and Large-eddy Simulation (LES) versus Reynolds Averaged Navier-Stokes (RANS) turbulence model. The penetration length exhibited limited sensitivity to these variations. However, local data such as the liquid volume fraction near the injector displayed significant differences, which could affect mixing and combustion predictions in engine simulations. These findings emphasize the need to reassess simulation assumptions and refine guidelines for accurately predicting spray characteristics in advanced engine modeling.