Application and Structural Optimization Analysis of Hydrofoils during Descent with Mission Payloads

Roll instability and landing deviation during the unpowered descent of deep-sea mission payloads pose significant risks to deployment safety and positioning accuracy. This study investigates the use of hydrofoil-based control surfaces to achieve roll reduction and passive trajectory correction following payload separation from unmanned underwater vehicles. An experimentally validated URANS-based numerical framework, combined with surrogate-model-assisted optimisation, is employed to analyse wake modification mechanisms and optimise hydrofoil configuration. The results demonstrate that the optimised roll-reduction hydrofoil significantly suppresses vortex-induced roll oscillations while maintaining a high descent velocity, despite the increased frontal area. In addition, the gliding hydrofoil enables effective positional correction by converting gravitational potential energy into horizontal motion during inclined descent. The proposed hydrofoil configuration provides a mechanically simple and energy-efficient solution for stabilised deployment of deep-sea mission payloads.