Fish-inspired Propulsion For Remotely Operated Surfaces Ships And Underwater Vehicles
Project Description :

Aquatic animals propulsion systems are classified based on their modes of propulsion such as lift, drag, undulation and jet. in lift-based propulsion, aquatic animals use their fins as propulsors. for birds, the upward forces, (lift) is generated when there is a pressure difference between the upper surface and lower surface of the wing. in order to keep the lift with a component facing forward, the angle of attack of their fins is adjusted by rotating or swinging them. flapping in the vertical plane is the most common mode in insects, birds, bats and aquatic animals, where the wing movement consists of down stroke (generating positive lift) and upstroke (generating negative lift). superimposed on this is the wing rotation to adjust the angle of the wing to enable a change in direction of motion. down stroke is termed as the power stroke, producing positive lift while the upstroke is a recovery one, producing negative lift. in principle, lift can be generated on either the up or down stroke of the appendage. however, in life many organisms emphasize or completely rely on the down stroke (eg: sea turtles, penguins and sea lions). besides the basic flapping motion, the fin movements exhibit different trajectories like 8-shaped, ellipse etc., geared towards producing lift and thrust during different phases of movement such as acceleration/deceleration, cruising, hovering, take-off and landing. in undualtion mode, the inspiration from the propulsion system of a tuna fish, which uses its caudal fin for movement, is considered for study. the fin will have oscillatory mechanisms which can be operated remotely. the fastest and most efficient swimming of fishes are categorized as thunniform (e.g: tuna). thunniforms generate undualtory sine wave by using rear part of tail peduncle. the wavelength of undulation is long, and wide at trailing edge of the caudal fin. it provides thrust mainly by their stiff caudal fin. the angle of attack of the caudal fin changes once it reaches its maximum amplitude in order to maximize the thrust. thunniforms caudal fin is crescent-shape with high aspect ratio. their caudal fin is stiff, however, it shows a slight flexibility during powerful stroke. the span of the caudal fin does not change except for some type of thunniforms which have very small change. during the stroke of the caudal fin, the centre of the caudal fin is leading and the tips are trailing edges. fish tail locomotion consists of combined sway and yaw motions. less than half of the body undulation is present in the posterior of the body. both tail and caudal fins contributes to the resultant thrust which helps the fish to move. the caudal fin is of forked shape, with higher vertical span compared to its horizontal extent. a necessity for a marine vehicle to achieve a high level of propulsive efficiency, maneuverability, low cavitation, wake reduction and improved stealth characteristics enthused scientists to consider biomimetic approaches to underwater vehicles. in the present research, both lift-based and undulation mode is considered for remotely operated surface ships and near surface underwater vehicles. a undulation type caudal fin is fitted for a remotely operated surface ship of length 1.5 m model. this study also presents lift based propulsion consists of two pectoral fins located on the forward side of the near surface underwater vehicle along with the caudal fin. strain gauge force transducers are used to measure the forces on caudal fin in surface ship case and in underwater vehicle tests. similarly the forces are measured on both pectoral fins of underwater vehicle. the thrust measured in bollard pull and self propulsion test are presented in the current research.

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Project Details :
  • Date : Nov 30,2016
  • Innovator : Mannam Naga Praveen Babu
  • Team Members : Mannam Naga Praveen Babu,Krishnankutty. P
  • Guide Name : Prof. P. Krishnankutty
  • University : Indian Institutes of Technology Madras
  • Submission Year : 2017
  • Category : Naval Engineering
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