Design optimization and combined numerical-experimental investigation of the hydrodynamic performance of underwater disc-shaped gliders

The disk-shaped underwater glider is widely used in marine environmental monitoring due to its excellent underwater gliding capability. Gliders can be equipped with various sensors such as hydrophones and other acoustic acquisition devices. The lift-to-drag ratio of the glider’s molded lines and hydrodynamic noise during gliding are key factors influencing its underwater glide performance and acoustic data reliability. This study focuses on multi-objective optimization design for the lift-to-drag ratio and hydrodynamic noise of underwater gliders. First, the glider profile is parameterized using Hicks–Henne functions. Subsequently, a multi-objective optimization mathematical model is established with the lift-to-drag ratio and hydrodynamic noise as optimization objectives. NSGA-II (Non-dominated Sorting Genetic Algorithm II) is employed to perform the optimization design. Finally, numerical simulations and water tunnel testing are conducted to validate the effectiveness and accuracy of the proposed optimization methodology. Hydrodynamic performance and noise characteristics of full-scale underwater glider models (both pre- and post-optimization) were evaluated through CFD simulations. In addition, scaled models based on similarity design theory were developed for water tunnel testing, where lift/drag forces and acoustic signatures were systematically measured. Numerical simulations and model experimental results demonstrate that the optimized discoid glider exhibits an improved lift-to-drag ratio across the designed operating condition range, along with a reduction in hydrodynamic noise. The optimization outcomes satisfy the predetermined objectives, confirming the effectiveness of the optimization methodology. This study provides theoretical and methodological guidance for the application and development of discoid gliders.