A controllable main wing module design and working strategy for a water-jet hybrid underwater glider

A water-jet hybrid underwater glider (WJHUG) is a hybrid-driven underwater glider (HUG) developed by Huazhong University of Science and Technology (HUST) that has a gliding mode, a fixed depth propulsion mode, and a hybrid gliding mode. However, the fixed hydrodynamic shape cannot satisfy the application requirements of the WJHUG to operate in multiple modes. To realize an actively changing hydrodynamic shape in a WJHUG, we propose a controllable main wing module (CMWM) design concept. The specific layout scheme and actuator design of the CMWM are presented. Using surrogate-based optimization (SBO), the optimization of the rectifier appendage design for the CMWM is accomplished. Analysis of the WJHUG working strategy with the CMWM is carried out by global optimization for the optimal variable wing angle under different modes. Compared with the original model, the final evaluation results show that the lift-to-drag ratio in gliding mode of the WJHUG with the CMWM was improved by a maximum of 9.4%, and the drag was decreased by a maximum of 21.5% under small angles of attack (AOAs) in fixed depth propulsion mode. Finally, the strong performance of the CMWM design and working strategy are verified by field experiments.