Hu, Gang

Aerodynamic modification on slender structures for enhancing wind energy harvesting

Abstract eng:
The past few years saw a number of studies on piezoelectric energy harvesters (PEHs) being developed as sustainable power sources. Aeroelastic phenomena of bluff bodies have been widely adopted as a kinetic energy source for the wind energy harvester, and they mainly include vortex induced vibration (VIV), galloping, and flutter. Different strategies to improve the efficiency of these PEHs have since been proposed and studied. Aerodynamic treatment of the bluff body is one of the most effective approaches. In spite of the high efficiency of the aerodynamic treatment for enhancing the performance of wind energy harvester, relevant studies are rare. Thus, it is worth investing substantial effort in this subject. This paper presents the results of wind tunnel model studies of the wind-induced vibrations of circular cylinder and square prism and the effectiveness of aerodynamic modifications to enhance the vibrations for energy harvesting. For the circular cylinder, small diameter cylindrical rods were attached at different circumferential locations symmetrically from the windward generator along the stagnation line. For the square prism, protruding fins were fitted at different combinations of windward and leeward corners. The circular cylinder and square prism were mounted on a flexible cantilever on which a piezoelectric sheet was bonded. Harvested power was measured with the piezoelectric sheet connected to an electrical load. The test results show that two small diameter cylindrical rods affixed at 60°from the windward generator significantly enhanced VIV and lock-in behaviour of the circular cylinder to facilitate energy harvesting. Furthermore, wind energy was harnessed sustainably over the range of wind speed tested and well beyond the VIV onset wind speed. For the square prism, the fitting of two leadingedge fins also significantly improves the energy harvesting efficiency by up to 150%, compared to a plain square prism. This paper highlights the effectiveness of appropriate aerodynamic modifications to a circular cylinder and a square prism to enhance the aerodynamic instability of slender structures for wind energy harvesting.

Contributors:

Kwok, K.C.S.

Publisher:

l'Association pour l'Ingénierie du Vent

Conference Title:

7th European and African Conference on Wind Engineering

Conference Title:

7th European and African Conference on Wind Engineering

Conference Venue:

Liège, BE

Conference Dates:

2017-07-04 / 2017-07-07