Wind Harvesting (Small scale wind turbine, Galloping and VIV)
2020 – 2021
أ.د. حسن الجمل
Wind harvesting is the use of wind to provide mechanical energy through wind turbines to turn electric generators for electrical energy and it depends on two variables of wind direction and speed. Our used types in this project are: –
- Small scale wind turbines
- It known as micro wind turbines, are used for microgeneration of electricity, as opposed to large commercial wind turbines, such as those found in wind farms. Small wind turbines often have passive yaw systems as opposed to active ones. They use a direct drive generator and use a tail fin to point into the wind, whereas larger turbines have geared powertrains that are actively pointed into the wind.
- Small scale wind turbine is considered one of the vertical axis wind turbines which can handle air flow from more than one direction. This type of turbine is characterized with high wind collecting capacity and easy maintenance.
- The generators of small turbines often have a significant resistive torque that must be overcome aerodynamically before the blades will start turning. The two main differences are their much higher rotational speed, which causes more fatigue cycles and higher yaw moments, and their operation at low Reynolds number, which means that thick aerofoil sections cannot be used near the root.
- Vortex-induced vibration (VIV)
- It is probably the single most important design issue for steel catenary risers, particularly for high current locations. High frequency vibration of the riser pipe due to vortex shedding leads to high frequency cyclic stresses, which can result in high rates of fatigue damage.
- Aluminum sheet attached to an artelon base with 2 bluff bodies (cube and ellipse) fixed at the top of the sheet. The sheet has 3 piezoelectric material in every side of it to generate electricity the piezoelectric are connected in series to generate the biggest electricity from them.
- The model is fixed in the wind tunnel to test it. The model is placed in line with the direction of the flow. When the flow hits the bluff body the vortices are initiated. And the sheet starts to vibrate and generate electricity from piezoelectric material.
- The galloping energy harvester, a curved blade oriented perpendicular to the flow, can produce self-sustained oscillations at uncharacteristically low wind speeds. The dynamics of the harvesting system are studied experimentally and compared to a lumped parameter model. Numerical simulations quantitatively describe the experimentally observed dynamic behaviour. Flow visualization is performed to investigate the patterns generated by the device. Dissimilar to many other galloping harvester designs, the flow is found to be attached at the rear surface of the blade when the blade is close to its zero-displacement position, hence acting more closely to aerofoils rather than to conventionally used bluff bodies. Simulations of the device combined with a piezoelectric harvesting mechanism predict higher power output than that of a device with the square prism.
- A potential application for this device is to power wireless sensor networks on outdoor structures such as bridges and buildings.
- Two cantilever beams and a prism with an equilateral triangular cross section attached to the free ends make up a galloping energy harvester, the two beams and the prism are aluminium, the beams and the prism are connected to a cylinder and the base of this cylinder is from artelon to fix it in the wind tunnel, there are 4 ceramic piezoelectric material on each beam, the 8 piezoelectric are connected in series to obtain the largest voltage from them.