K.T. Tse

Enhanced Performance of Wind Energy Harvester by Aerodynamic Treatment of a Square Prism

This letter presents the effects that fitting fins to various corners of a square-prism galloping-based piezoelectric energy harvester (PEH) has on its performance, based on results from a series of wind tunnel model tests. The results show that attaching fins to the leading edge significantly improves the efficiency of the harvester, achieving a maximum power 2.5 times that attained by a plain square prism PEH. Furthermore, a length that is 1/6 of the prisms cross-sectional width is found to be optimal for fins that are attached to the harvester.

Performance of a circular cylinder piezoelectric wind energy harvester fitted with a splitter plate

This study examines effects of the splitter plate placed in the near wake of a circular cylinder on the performance of a piezoelectric wind energy harvester through wind tunnel experiments. The kinetic energy of the harvester is gained by wind-induced vibrations of the circular cylinder. The splitter plate is attached to the leeward side of the cylinder. The ratio of the splitter plate length to the diameter of the circular cylinder (Lsp/D) ranges from 0.25 to 2.00. After attaching the splitter plate with an appropriate length, the harvester is able to sustain large amplitude vibrations beyond the wind speed range corresponding to vortex-induced vibrations. Thus, the upper bound of the wind speed range for the harvester to harness wind energy is eliminated, which significantly increases the efficiency of the harvester. Compared to the different lengths of the splitter plate, 0.65D has been found to be the optimal length for maximizing the harvested power.

Unsteady Galloping Force and Response Prediction of a Slender Prism Using a Novel Wind Tunnel Test Technique

This paper examines a new measure of the unsteady galloping force of a slender prism using a hybrid pressure-aeroelastic test (HPAT) technique. The HPAT was performed to simultaneously observe the unsteady crosswind force and response of a test model. The observed crosswind force contains amplitude-dependent non-windinduced aerodynamic force that was caused by the interaction between the oscillating test model and the surrounding air. The unsteady galloping force of the test model was therefore evaluated by removing the non-wind-induced aerodynamic force identified by using a forced vibration technique from the observed unsteady crosswind force. The amplitude-dependent mechanical nonlinearities (damping and stiffness) of the HPAT system were identified by using a wavelet method from a free decay response of the test model. By substituting the obtained unsteady galloping force and the mechanical nonlinearities into the governing equation of motion of the test model, the galloping responses of the test model were predicted. The results show that the galloping responses of the test model predicted by the identified unsteady galloping force are identical to the experimentally measured response, and