Objective To investigate the motion characteristics and flow field properties of trans-medium submersibles during underwater straight navigation and turning maneuvers.
Method Based on the numerical simulation technology of computational fluid dynamics, the VOF multiphase flow model and the SST k-ω turbulence model are used to establish the numerical computation model of the underwater navigation of the transmedia submersibles. The validity of the numerical method was verified by comparing the total drag results from experiments on the submarine model (DARPA Suboff) at different speeds with the numerical calculation results. On this base, numerical simulations and analyses of the underwater straight navigation and turning maneuvers of the trans-medium submersible were conducted, focusing on the effects of conduit propeller rotation speed and tail fin deflection angle on the underwater straight navigation and turning performance of the submersible.
Results The research results indicate that during straight underwater navigation of the trans-medium submersible, the propulsion speed exhibits an approximately linear relationship with the propeller rotation speed. For instance, when the propeller speed increases from 600 r/min to 4800 r/min, the propulsion speed rises from 1.1 m/s to 8.1 m/s. Concurrently, the negative pitch moment increases with the propeller speed, while its absolute value gradually decreases (from −0.35 N·m to −0.17 N·m), indicating that the submersible maintains a stable attitude during high-speed navigation. The propeller speed has minimal impact on the surface pressure coefficient distribution and the flow field structure. During underwater turning, the turning radius is primarily influenced by the tail fin deflection angle and is almost unaffected by the propeller speed. The turning radius decreases as the tail fin deflection angle increases (from 3.35 times the submersible length to 0.75 times), but the reduction trend gradually slows. In contrast, the turning speed is jointly influenced by the propeller speed and tail fin deflection angle. The thrust of both propellers increases with higher propeller speeds and greater tail fin deflection angles. The thrust of the outer propeller in the turning trajectory consistently exceeds that of the inner propeller, with the thrust difference increasing as the tail fin deflection angle grows. Furthermore, during the turning motion, the tail fin deflection-induced motion results in a significantly asymmetric surface pressure distribution on the submersible. This asymmetry becomes more pronounced as the tail fin deflection angle increases and is closely related to the asymmetric flow characteristics of the surrounding flow field.
Conclusion This study can provide a reference for transmedia submersibles configuration design and underwater navigation performance analysis.
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