Modelling of In Nozzle Cavitation and Early Spray Breakup Using a Multiphase Volume of Fluid Method
A compressible, multiphase Volume of Fluid Large Eddy Simulation is implemented in the OpenFOAM environment. The volume fraction transport equations for liquid, vapour and gas phases are reformulated to include phase change source terms. These terms are modelled with the cavitation model by Schnerr, which is extended to eliminate non physical mass transfer rates. The numerical method is validated by comparing the simulated mass flow rates, pressure and liquid volume fraction distributions at different cavitation conditions against published experimental data. Favourable comparison between simulations and experiments is achieved with minor discrepancies attributable to uncertainties in fuel properties and assumptions made in numerical models. The application of the code to simulation of in nozzle phenomena and primary breakup of the spray injected from a sharp edged nozzle reveals that in nozzle flow separation, wall shear and cavitation contribute largely to the fragmentation of the jet.