S.B. Martynov

Numerical Simulation of Cavitation Flows Based on Their Hydrodynamic Similarity

Abstract Hydrodynamic similarity of cavitation flows in nozzles of different scales has been observed experimentally. In this paper a model of cavitation has been developed, taking into account the bubbly nature of cavitation and assuming local homogeneity of the vapour-liquid flow. The model of cavitation is built from correlations for evaporation and condensation, based on bubble dynamics theory, and an equation for the number density of cavitation bubbles, derived by assuming hydrodynamic similarity of cavitation flows. Compared with conventional models of cavitation, which fix the number density of cavitation bubbles, the present model takes into account the effect of liquid tension on the number density of active cavitation nuclei. The model has been implemented within the VECTIS computational fluid dynamics code and applied to the simulation of cavitating flows in nozzles.

Diesel fuel spray penetration, heating, evaporation and ignition: modelling vs. experimentation

The modified WAVE droplet breakup model, taking into account the transient processes during spray injection, the Effective Thermal Conductivity (ETC) liquid phase model, the gas phase model suggested by Abramzon and Sirignano, and the customised version of the Shell autoignition model have been implemented into the KIVA 2 CFD code. The observed Diesel spray tip penetration and Sauter Mean Radii show much better agreement with the prediction of the modified WAVE model compared with other droplet breakup models. The difference in the autoignition delay times predicted using the Infinite Thermal Conductivity (ITC) and ETC models is important for practical computations.