Optimization of 3D Hydrofoil Using a Cavitating Lifting Line Method
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Cavitation is a complex phenomenon that inevitably takes place in high-speed foiling. As such, designing a hydrofoil specifically for supercavitation is mandatory when striving for high speeds, but doing so with common engineering tools is slow and inefficient. To achieve the World Sailing Speed Record, Syroco and Cubit had to research more advanced and faster tools and processes to design the most efficient foil for the sailboat that will be used for the world record. Initially, the optimization of a high-efficiency 2D supercavitating profile was performed using an optimization loop that used an efficient Finite Volume Method (FVM) simulation setup for hydrodynamic performance evaluation coupled with structural Finite Element Analysis (FEA). However, despite the optimized FVM setup, a 3D optimization loop with 3D FVM simulations is unfeasible because of the prohibitive computational costs of 3D FVM. For this reason, ways to bypass 3D FVM have been explored for an optimization loop able to study and optimize 3D wings. This article introduces a new method for optimizing 3D supercavitating foils using a custom lifting line code called the Cavitating Lifting Line (CLL). The CLL accounts for cavitation nonlinearities and provides results with significantly reduced computational time compared to optimized FVM setups. This accelerated approach enables multi-level optimization, considering hydrodynamic, structural, and feasibility constraints, and allows for convergence towards the most efficient design. Our method represents a breakthrough in efficient optimization for high-speed sailing foils and has potential applications in other fields requiring 3D hydrodynamic optimization.
