LINKING NOZZLE FLOW AND PRIMARY BREAKUP OF HIGH PRESSURE DIESEL JETS USING CFD

In this paper, two models for the primary breakup of Diesel jets are analysed and compared, not only by means of simulations, but also to experimental data. Both models are based on the estimation of the potential breakup capability of the nozzle flow in order to obtain the size and velocity of the first droplets created out of the liquid jet. The used geometries for this investigation are real size nozzles like the ones encountered in passenger cars nowadays, operated under engine-like conditions. Unsteady simulations of the turbulent and multiphase flow inside the nozzle are carried out with the commercial 3D-CFD code CFX and are used as input for the spray simulations. Using this nozzle flow information, the primary break-up models of Tatschl [20] and Baumgarten [3] are applied to a standard injection case and their performance is evaluated. In the first case, the model is implemented in the 3D-CFD code FIRE, whereas CFX is used in the latter case.

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