ABSTRACT
Recent progress in numerical simulations and experimental research has led to a better understanding of cavitation, enabling engineers to predict and alleviate its adverse effects on hydrofoil performance. Cavitation is often unavoidable for lifting surfaces operating beneath the free surface even at low speeds, and should be accounted for at early design stages. Sheet cavitation, a multiphase phenomenon by definition, can be predicted however using ideal flow models. These prediction models are based on the assumption that the attached cavity, whose termination region is dictated by a cavity termination model, is a free streamline. In this work, following an inverse problem formulation, a new prediction model for partially cavitating hydrofoils steadily moving beneath the free-surface is proposed. The sensitivities required for the gradient-based algorithm are derived using the continuous adjoint method. The proposed numerical scheme predicts well the cavity shape and the cavitation number, under the “fixed cavity length” assumption, when compared against experimental data and other methods. Finally, the present method could facilitate the preliminary design of lifting surfaces with, or without, free-surface effects.
