3-D High-Fidelity Hydrostructural Optimization of Cavitation-Free Composite Lifting Surfaces
Y. Liao, J. R. R. A. Martins, and Y. L. Young
Composite Structures, 268113937, 2021
Design and manufacturing technologies have promoted the use of composites in hydrodynamic lifting surfaces. Composites, even with state-of-the-art coatings, are susceptible to cavitation erosion damage. This work aims to design a cavitation-free composite lifting surface to maximize efficiency while ensuring structural integrity. We optimize a canonical hydrofoil using a gradient-based optimization framework that couples a Reynolds-averaged Navier–Stokes solver with a finite-element structural solver. The optimization reduces the weighted drag coefficient by 1.2% over lift coefficients between 0.2 and 0.6, and increases the cavitation inception speed by 82% at the nominal condition compared to the baseline. The optimized design shows higher cavitation inception speeds than an Eppler hydrofoil (E1127, known for cavitation-free operation at moderate lift conditions) with the same baseline planform at CL >= 0.2. The improvement from the E1127 hydrofoil was due mostly to delaying tip vortex cavitation induced by 3-D effects. The optimization finds the fiber angle to balance the bend-twist coupling and modifies the directional strength to reduce the susceptibility to excessive deformation and material failure when sweep presents.