A Numerical Characterization of New High-Pressure Multi-Hole GDI Injector

The paper reports a numerical activity aiming at investigating the spray structure originated by a new-generation GDI injector. The spray is analyzed under quiescent conditions, injecting the fuel in a test vessel at non-evaporative ambient conditions. Results from 3D-CFD simulations are compared to experimental measurements available in literature: commer-cial gasoline at two different injection pressures (10 and 20 MPa) was injected and the spray evolution was ana-lyzed throughout the injection duration.The spray was investigated along the jet axis by the phase Doppler anemometry in order to provide droplet size and velocity, in terms of both axial and radial components. Data were analyzed using the ensemble averaging technique in order to provide mean values.Experimental measurements briefly described above are used to test and validate some lagrangian spray numerical sub-models and numerical parameters such as grid density, numerical setup, primary and secondary fuel breakup and droplet to droplet interaction. Particular care is devoted to the accurate representation of the spray primary breakup, in view of the lack of ad-hoc developed models available in literature. A wide CFD activity is then performed in order to investigate grid effects on the prediction of liquid spray penetration and droplet velocity.Results from the CFD analyses show a relevant dependency of the spray structure on both the computational cell size and the adopted CFD model ensemble.