School of Engineering and Materials Science
Research Student Awards
PhD Thesis: Analysis of hydrodynamic forces on flapping wing
Author: LA MANTIA, Marco
Supervisor(s): Peter Dabnichki
The work is devoted to a theoretical and experimental analysis of flapping-wing propulsion. The particular focus is on wing oscillating in water and Reynolds numbers order of 10 to the power 4.
A computational program based on a potential flow Boundary Element Method was developed to evaluate the forces acting on a harmonically heaving and pitching wing. The program was initially devised for two-dimensional problems (i.e. wing of infinite span) and three dimensional effects, such as wing-tip vortices, were later taken into account. A novel formulation of the unsteady Kutta condition, assuming finite pressure difference at the trailing edge of the moving wing, was proposed and implemented. Comparisons with published experimental data showed good agreement with the computational results. The influence of inertia related effects, such as the added mass, on the thrust production was investigated as such an analysis had not been presented before and is particularly relevant to unsteady motions in water.
An experimental rig was designed to test harmonic heaving propulsion modes. The motion pattern was generated by a purpose-made cam connected to an electric motor. The structural analysis of the oscillating wing was performed in the process as similar issues were not extensively addressed in the past. A series of wind tunnel experiments was then run to validate the computational results.
It was proven through a number of numerical and experimental tests that the developed computational method produces consistent prediction of the hydrodynamic forces, specifically the thrust, which was the main goal of the work.