Design and hydrodynamic evaluation of an open-frame underwater robot

Purpose This study aims to design and analyze a frameless underwater collecting robot that integrates a six-thruster propulsion system with a suction-based harvesting mechanism to improve underwater mobility and capture performance. Design/methodology/approach Computational fluid dynamics (CFD) simulations were conducted to investigate the influence of the frame-less structure on flow field characteristics, drag variation at different speeds and vortex shedding caused by boundary-layer separation. The dynamic pressure distribution near the open-frame wall regions was also analyzed. A functional prototype was fabricated, and water tank experiments were performed to validate the simulation results. Findings Results show that the frameless structure effectively reduces near-wall dynamic pressure and stabilizes the flow field. The robot achieved a maximum horizontal velocity of 1.3 m/s and demonstrated enhanced maneuverability with a four-thruster circular configuration. The suction-based collection system successfully captured and stored underwater targets. Originality/value This research introduces a novel integration of frameless structural design and suction-based capture strategy, supported by a validated CFD framework for multi-motion hydrodynamic analysis. The findings provide theoretical and experimental guidance for optimizing open-frame ROV design and improving underwater operational efficiency.