Comparison of bio-inspired flapping foil propulsion systems with rotary propulsion

Conventional rotary thrusters used in underwater Remotely Operated Vehicles (ROV) suffer from disadvantages such as high noise, entangling with floating objects and limited efficiency. Our group has studied bio-inspired propulsion with a single caudal fin which overcomes some of these disadvantages. However, it still faces some problems such as low thrust density (thrust generated per unit volume of the thruster), pitch/yaw and centre of mass (COM) oscillations in the body increasing the energy cost of transport. The solution being proposed is a novel dual flapping foil arrangement actuated using a single motor which tackles the limitations of single flapping foil. Comparison of efficiency, maximum thrust and thrust density has been performed between single and dual flapping foil propulsion. Also, this solution is benchmarked against commercially available rotary thrusters. The results showed that thrust density of bioinspired propulsion was not at par with rotary thrusters. However, the efficiency obtained was comparable.