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A 1D flash evaporation model is being developed to capture the effects of bubble nucleation and growth inside multi-hole injector nozzles to investigate the flash evaporation in fuel injector sprays in Gasoline Direct Injection (GDI). The 1D nozzle flow model helps to understand the effects of main physical and geometrical parameter in promoting the fuel flash evaporation. This model is based on a weakly compressible homogenous two-phase mixture assumption. A non-equilibrium model is used to predict the vapour formation rate along the nozzle. A fully explicit method based on a two-step Lax-Wendroff method is used together with a TVD scheme. An atomisation model has been proposed to correlate the void fraction at nozzle exit to probability function of the liquid droplets generated from flashing atomisation. An accurate two phase speed of sound is adopted allowing one to predict the choked flow conditions once saturation has been reached.

This paper deals with a CFD three-dimensional multiphase simulation of rotary vane pump. The paper presents a suitable methodology for the investigation of the cavitation effects and/or incondensable gases. All the 3D simulations were performed by using Fluent v12 (Beta version). A moving mesh methodology was defined to reproduce the change-in-time shape of the internal pump volumes. In particular, the pump analysis was focused on the generation, and evolution of the cavitation phenomena inside the machine to identify the locations where this phenomena could occur. Moreover, the influence of incondensable gas dissolved inside the operator fluid on both pump performance and cavitation evolution was evaluated. Significant results were obtained about the analysis of incondensable gas influence on the cavitation evolution showing that, today, CFD analysis can provide detailed information on such harmful phenomena which can not be achieved by experiments.

The evaluation of the steady-flow discharge coefficient of ICE port assemble is known to be very sensitive to the capability of the turbulence sub-models in capturing the boundary layer dynamics. Despite the fact that the intrinsically unsteady phenomena related to flow separation claim for LES approach, the present paper aims to demonstrate that RANS simulation can provide reliable design-oriented results by using low-Reynolds cubic k-ε turbulence models. Different engine intake port assemblies and pressure drops have been simulated by using the CFD STAR-CD code and numerical results have been compared versus experiments in terms of both global parameters, i.e. the discharge coefficient, and local parameters, by means of static pressure measurements along the intake port just upstream of the valve seat. Computations have been performed by comparing two turbulence models: Low-Reynolds cubic k-ε and High-Reynolds cubic k-ε.

Injection rate profile is a powerful tool to control engine performance and emission levels. In particular, the Common Rail (C.R.) injection system has allowed flexible fuel injection in DI-diesel engines by permitting a free mapping of the start of injection, injection pressure, rate of injection and, in the near future, multiple injections,. This paper deals with improvements of stable operating condition limits of the Common Rail injector for multiple injection purposes. The focus was to optimize the behavior of the solenoid valve in order to reduce the minimum time interval between two consecutive injections required for system stability. An extensive experimental characterization of the valve has been performed in order to measure the main mechanical and electrical parameters of the assembly components. The experimental and the numerical studies have allowed optimizing the current profile and consequently the design of the anchor pin-ring assembly of the solenoid valve.

A flash evaporation model is being developed to capture the effects of bubble nucleation and growth inside multi-hole injector nozzles to investigate the flash evaporation in fuel injector sprays in Gasoline Direct Injection (GDI). The 1D flash evaporation model is a key tool for providing the 3D Eulerian-Eulerian or Lagrangian spray simulation model with the right droplet size in order to properly predict the effect of degree of superheating on mixture formation. Super heating conditions are likely to be found under partial load conditions in GDI applications or they might be deliberately induced to enhance fuel atomization and vaporization. A quasi-1D nozzle flow model has been developed to help quantifying the effects of main physical and geometrical parameters in promoting fuel flash evaporation. This model is based on an weakly compressible homogenous two-phase mixture assumption. A non-equilibrium model is used to predict the vapour formation rate along the nozzle.