Numerical Simulation of Diesel Injector Internal Flow Field

In Diesel engines, fuel-air mixing process and spray evolution drastically affect combustion efficiency and pollutant formation. Within this context, a detailed study of the effects of injector geometry and internal flow is of great importance to understand the effects of turbulence and cavitation on the liquid jet atomization process. To this end, both numerical and experimental tools are widely employed. Objective of this work is to simulate the complex flow behavior inside the injector nozzle taking the most relevant physical phenomena into account. CFD simulations were carried out using a compressible solver with phase change modeling available in the OpenFOAM framework. In particular, cavitation was modeled by using an homogeneous equilibrium model based on a barotropic equation of state while the RANS k-ω SST model was used for turbulence. Experiments performed at Kobe University (Japan) on simplified nozzle geometries were used to validate the proposed approach in terms of velocity and vapor distributions. A rather good agreement between computed and experimental data was achieved in terms cavitation length, mass flow, momentum flux making possible to apply the proposed methodology also to real injector configurations in the near future.