Shape Design For A Hybrid-driven Underwater Vehicle Based On CFD

Autonomous Underwater Vehicle (AUV) is usually driven by a propeller. It has high maneuverability and speed, but a relatively short range. Autonomous underwater glider (AUG) is a new type of underwater vehicle propelled by buoyancy. The underwater glider travels in a saw tooth pattern with a low speed. It It can continuously travels in the order of several thousand kilometers. But compared with AUV, its maneuverability is low and can only travel with a low speed. Considering the respective advantages of the AUG and the propeller driven AUV, a hybrid-driven underwater vehicle that is equipped with both buoyancy-driven system and propeller driven system has been designed. In this paper, shape design of the hybrid-driven underwater vehicle has been conducted for the particular underwater working environment. The shape of the vehicle has been optimized through drag calculation and parameter analysis. The main results and contributions are as follows:1. Numerical simulation is superior to experiments in that shorter time and lower cost are required. However, no conclusion has been reached on the ideal numerical model that is suited for underwater vehicle design. Using computational fluid dynamics (CFD) method, the drag force on the vehicle has been calculated by solving RANS equations with different viscous models. Comparison between simulation results and experimental results indicates that the SST k-ωtwo-equation viscous model is the most appropriate model for drag calculation.2. The fineness ration (body length/maximum diameter) is one most important parameter that affects the drag force on the underwater vehicle. A drag force versus fineness ratio curve has been obtained using the SST k-ωtwo-equation viscous model and the numerical calculation has been implemented by the commercial CFD software FLUENT. The result illustrates two low drag ranges, which can be used in design and optimization of the shape of the vehicle body and the ballast tanks.3. A hybrid-driven underwater vehicle is actually a result of structure combination of AUV and AUG. Wing design for the hybrid-driven vehicle is also discussed, regarding the vehicle's performance in endurance, stability, and maneuverability. Suggestion on a folding wing design has also been given for the hybrid-driven underwater vehicle.