Abstract
The maneuverability and hydrodynamic performance of the tethered underwater robot in a uniform flow field is investigated. In this research, a tethered underwater robot symmetrically installed with NACA66 hydrofoils and Ka 4-70/19A ducted propellers around its main body is first constructed. The method of overlapping grid combined with sliding mesh is applied in the numerical simulations, and the principle of relative motion is adopted to describe the hydrodynamic responses of the tethered underwater robot during the robot manipulation. The reliability of the CFD methods applied in this research is verified by experimental results, and the comparison between numerical and experimental ones shows that there is very little difference being found. The numerical results indicate that computational cost due to the research’s large-scale domain can be effectively reduced by the adopted numerical methods, hydrofoils’ control effect is greatly influenced by the towing speeds, and thrusts issued from the ducted propellers are related to the tethered underwater robot’s position and towing speed.
Highlights
Many resources in the complex ocean environment can be widely explored by the tethered underwater robot because it can execute a lot of tasks in searching hydrologic features or observing the ocean environment [1]
The tethered underwater robot coupling the rotation of the ducted propeller and the swing of hydrofoil is towed at different speeds in a uniform flow field
The average amplitude of heave increases by 179.85% as the towing speed increases to 5 knots. These results suggest that the trajectory of the tethered underwater robot is mainly influenced by the towing speed
Summary
Many resources in the complex ocean environment can be widely explored by the tethered underwater robot because it can execute a lot of tasks in searching hydrologic features or observing the ocean environment [1]. Methods to investigate the dynamic performances of a tethered underwater robot can be classified in two ways: experiment study and numerical simulation. Wu et al proposed an integrated hydrodynamics and control model coupling the undersea environment’s hydrological factors to simulate a tethered underwater robot system [10], and the result is validated by experiment [11]. In order to simulate the complex motion of the tethered underwater robot in the working environment, a valid CFD method based on the governing equation of flow field, cable, and six-degrees-of-freedom model is proposed. The simulation of the rotation of control equipment is applied with the sliding mesh, and the hydrodynamic performance of the tethered underwater robot by controlling the swing of hydrofoils or the rotational speeds of propellers is investigated in the Simcenter Star-ccm+2020.1. Prandtl numbers for k and ε; Sk and Sε are source terms
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