Background Information:
Wind turbines are used to capture solar energy (wind) to create mechanical energy (the turning of the repellers) and then turn this mechanical energy into electrical energy. The wind turns the repellers which then becomes the input mechanical energy into a simple generator. This is done by rotating magnets that are surrounded by coils of wire. The magnets cause a change in the magnetic field as they move, as in our design we alternated the magnets between north and south poles so that the change was greater. The change in magnetic fields induces a voltage in the coils of wire which causes an electric current. This is how wind turbines generate energy that we are conveniently able to use.
Materials and Methods:
My group used the following materials:
PVC pipe
wooden rods, 2 different sizes
cardboard
wire coil
4 small magnets
two round wooden attachments, two different sizes
We used the PVC pipe as the "tower" of our turbine. Then we used two PVC attachment pieces to create a "neck" at the top of the tower which would house the basic generator we made and connect to our wind catching device. We created blades by hot glueing pieces of cardboard to three wooden rods. We then cut the tips of these rods so that they had a flat surface and we used wood glue to fasten them to a wooden connector piece, the type that is typically used for a knob of some sort. To reinforce the glue, we put a screw through the rods. Tis connector piece has a hole in its center which we widened with a drill. Through this hole we slid another, thinner, wooden rod. We put another smaller wooden connector piece on this rod as well, towards the center of the rod. This piece had four small magnets glued onto it, evenly spaced. The north side of two of the magnets was facing out, while the south side of the other two was facing out. We were sure to alternate the polarity in order to create a consistently changing magnetic field. This piece with the magnets was placed just over the wire coils so that they could affect it with their magnetic field. The wooden rod that held this piece continued through this tunnel of PVC pipe and out the other end. On each side we put a small cardboard disk with a hole drilled in it for the rod to go through so that we could keep the repellers and the magnets suspended. The wire coil was pretty thick so that we could generate voltage. Each end of the wire had to be sticking out so that we could measure the changing voltage and see if our turbine was working. We ran one end of the wire down the PVC tower and taped it to the outside of the pipe. The other end we stuck out the PVC attachments at the "neck" region of the turbine. We scraped the outside of the wire off so that voltage could be read.
Results and Discussion:
The amount of voltage induced by our turbine was effected by the thickness of the coil of wire- or how many turns it had. We wrapped ours for a long time, we did not count the turns but it is suggested that when in doubt, keep wrapping. Also the magnets had to alternate in polarity. This was a problem because the magnets wanted to keep sticking together. We had to cover them with our hands while we were glueing them onto the wooden attachment. Hot glue worked fine but I would advise keeping the magnets away from metallic items once they have been glued on- we had some problems with this and had to re-glue. Keeping our design as simple as possible worked out well for my group. The cardboard worked just dandy as a way of keeping the rod in place that attached the spinning device to the magnet. Our biggest difficulty was inserting the coil into the turbine but we were lucky to have built the tower and neck parts with easily detachable pieces. We forgot to leave both ends of the coil out so that is something to keep in mind when designing your turbine and wrapping your coil.
Here's a video of our turbine in action:
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