Wave-assisted propulsion for autonomous surface vehicles

Gauthier, Matt (2018) Wave-assisted propulsion for autonomous surface vehicles. Masters thesis, Memorial University of Newfoundland.

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Abstract

Renewable energies, such as solar and wind, have been employed in the recent past to power and propel unmanned marine vehicles. In most cases however, the possibility of using wave energy is not considered. Therefore, in this thesis project, the thrust generating capacity of an oscillating hydrofoil in head seas is investigated. A mathematical model is presented that computes the forces on a two-dimensional hydrofoil oscillating in pitch. Existing empirical force coefficients are used to estimate the horizontal and vertical forces generated by the hydrofoil based on the effective angle of attack. A simulation case is then developed in OpenFOAM enabling the effects of wave height, wave frequency, foil pitch amplitude, and forward speed to be studied. To evaluate theoretical and simulation results, a hydrodynamic testing platform is developed using a DC motor to actuate the foil and a four load cell arrangement to measure forces. The experiments are performed in the wave tank of Memorial University of Newfoundland. Design of experiments methodologies are used to develop regression equations for simulated and physical data. A comparison of both model equations reveals that the simulation model is slightly offset from the physical model; however both models show that thrust can be achieved in head seas by using an actively pitch-controlled hydrofoil in low current conditions.

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