A Modified Bubbly Isenthalpic Model for Numerical Simulation of Cavitating Flows

This paper presents the development of a quasi-homogeneous isenthalpic cavitation flow model, suitably modified to account for the effects of thermal cavitation and the concentration of active nuclei. The proposed modified bubbly isenthalpic cavitation model has been implemented in a 2D numerical code in order to readily assess, by comparison with experimental results from the literature, its potential for the simulation of cavitating flows. Two types (hemispherical and 2-caliber ogival) of axisymmetric headforms and a 2D modified NACA 66-109 hydrofoil have been chosen for validation of the model against available data (Rouse & McNown, 1948; Shen & Dimotakis, 1989). The flow temperature has been varied from to in order to highlight the influence of thermal cavitation effects. Good agreement of the model predictions with the available experimental data has been found in terms of pressure distribution, extension of the cavitation region and loads (forces and moments) on the hydrofoil. As expected, the results indicate that the stability of the numerical method is sensitive to the temperature of the flow and to the presence of recirculating regions in the flow. Convergence problems have been detected at high angles of attack and when approaching room temperature, as a consequence of the inherent unsteadiness of reverse flow regions and the extremely rapid changes of the flow density in the absence of significant thermal cavitation effects. Examples are presented to display the influence of the relevant flow parameters on the solution.