• cavitation
• CFD
• injector
• LES
• OpenFOAM

The present thesis intended to make a comparison between different numerical codes, both commerical (STARCCM+) and open source (OpenFOAM), to assess performances regarding cavitation simulations for fuel injector in cavitating conditions.

Injector flows are characterized by cavitation interacting with turbulence in channels of very small size, making simulations very challenging. As for cavitation modeling, we adopt a popular homogeneous-flow model, in which the mass transfer due to cavitation is given by the Schnerr-Sauer model together with the classical Rayleigh- Plesset equation.
Concerning turbulence modeling, we adopted a Large Eddy Simulation approach, which proved to well represent the dynamics of large-scale turbulence structures even for rather complex flow configurations.

The reference test-case is a simplified throttle geometry for which both numerical and experimental data are available in the literature. This test-case is characterized by a liquid-into-liquid injection, thus reproducing a 2-phase flow condition and, despite the geometrical simplification, contains all the main difficulties encountered in practical applications, such as cavitation, turbulence, small dimensions and high-pressures.

Simulations have been carried out with different grid resolutions and time-steps to assess quantitatively and qualitatively the effects on the results. In particular, we found that flow instabilities may occur for a carefully choice of the numerical time-step. Present numerical results can give a further insight into the complex interaction between cavitation and turbulence, since high-pressure and small geometrical dimensions make experiments prohibitive.