Masters Thesis: Flow Induced Vibration Harvest

This thesis studies ways of broadening the range of a piezoelectric flow induced vibration harvester. The proposed device consists of a flap connected with a hinge to a spring. Existing harvesters are designed to replace or charge batteries for low power systems in the range of milliwatts. These systems produce low amounts of power, but for low flow speeds. The objective of this thesis is to increase the range of efficient harvesting. To achieve such a harvester, the coupling between the spring dynamics and aerodynamics will be studied. Considered methods for changing the dynamics of the spring are stiffness and length modifications. Besides changing the aerodynamics of the wing will also be considered as a solution. Linear state space models are derived and validated with experimental tests. After derivation of the models, changes in aerodynamics will not been seen as a feasible solution because of the required power transfer across the hinge. Despite stiffeners can contribute to the efficiency of a harvester by changes in the mode shape. Additional stiffness resulted in lower eigenfrequency changes than expected. Only the changes in length seem to have a significant influence on the range of harvesting. Master of Science Thesis Jim Kok