Wind Turbine Model
By Layton Oliveria, Kennedy Wesley, and Katherine Santora
By Layton Oliveria, Kennedy Wesley, and Katherine Santora
Section 1: Background (How They Apply to the Wind Turbine Model)
Primary Physics Concepts to know
1.) Electromagnetic Induction: It is the act of inducing voltage by changing the magnetic field in loops of wire. You take a loop of current carrying wire, in which when a magnet (going through, above, or near) will change the b (magnetic field) of the loop of wire, which will induce a voltage that can change the current. This current is used for a variety of things. We use this concept in our generator.
2.) Torque: Torque causes rotation. The two things torque requires is a force and lever arm. The Formula to find a torque is Force x Lever Arm. A lever arm is the distance from the axis of rotation to where the force is applied. The lever arms were our blades which were attached to the rod that was the axis of rotation. The force applied by the wind to the blades got the blades to spin.
3.) Friction: There are two things that affect fraction. The first is the nature of the the surfaces (this has nothing to do with speed or surface area) meaning rough or smooth. The second is how hard the surfaces are pushed together. This applied to our turbine in that, the inside of the box had a rough surface area. This means that it was harder for the the brass rod to spin inside of the rough surface. The amount of friction was increased by the heavy weight of the magnets, which pushed the brass rod harder against the hole in the box. Lastly, we also experienced friction when the blades were farther from the center of mass. The blades being farther from the generator box pulled the brass rod forward. In turn, the magnets were pulled against the inside of the generator box. Since the surface of the box is rough, it'd created some friction that slowed the velocity of our wind turbine model.
4.) Newton's Laws
- Newton's First Law: Newton's First Law states (the Law of Inertia) ," an object at rest or an object in motion will remain at rest or in motion at the same speed in the same direction, until acted upon by an outside force." Basically, the blades of the wind turbine will remain at rest until acted upon by the outside force of the wind. Once they are acted upon, they will continue to be in motion until acted upon by an outside force such as friction.
- Newton's Second Law: In word form, Newton's Second Law states that, "Force is directly proportional to acceleration, mass is inversely proportional to acceleration." In symbols that would be written as a=f/m. This applies to our wind turbine in that the greater the force of the wind is, the greater the acceleration of the blades will be. In addition, the greater the mass of our wind turbine, the lower the acceleration will be.
- Newton's Third Law: Newton's 3rd Law states that, "for every action there is an equal and opposite reaction." In our wind turbine, the wind pushes the blades ---> the blades pull the wheel --> the wheel pushes the brass rod --> the brass rod pulls the magnets. These are action reaction pairs.
5.) Rotational Inertia and Tangential Velocity
- Tangential/Rotational Velocity: The number of rotations or revolutions per unit of time. This is directly proportional to the tangential velocity. Tangential velocity depends on the radial distance from the axis of rotation. This applies to our turbine in that the longer the blades are, the farther they are from the axis of rotation. The farther away they are, the lower the tangential velocity will be. The larger the wheel/blades are the lower the number of the RPM's (rotations per minute) will be.
Section 2: Materials and Methods
Materials Needed
- 6 PVC Pipes + 4 PVC elbows + 3 triple sided PVC connectors
- 2 Rubber Washers (can differ in size depending upon the size of the hole you cut)
- 4 (2 inch) rectangular magnets
- 1 Brass rod
- 1 (2D) Circle of Basswood
- 1 Empty (2 Liter ) Plastic Bottle
- 10 (4 inch) Wooden Dowels
- 10 (4 inch) strips of cardboard
- 10 (2 inch) strips of cardboard
- 1 tube of Hobby glue (like Krazy glue)
- 1 cardboard box
- Copper Wire
- Electrical tape
- 1 Wooden Button
Methods
A.) The Magnet Placement
B.) Coils
Step two: After glueing the box closed, we grabbed copper wire because it is a good conductor of current. We wrapped the wire twenty- one times around each side of the box. It is crucial that you make sure the wire is perpendicular to the moving magnets. Otherwise, the current carrying wire will not feel a change in the magnetic field because it'd be parallel. Then we connected the two coils and scrapped the top of both ends of each of the coils. It is important that you scrape the same side of each wire, otherwise there will be current flowing one way and right back again, and the blades would not move. We twisted one end from each coil together in the front and wrapped electrical tape around them to ensure they wouldn't come apart. We did the same process on the back, but without the electrical tape so that we could connect them to the machine that'd test the amount of current we generate.
C.) Wind Catching Device
Step three: We the two liter plastic bottle and cut the sides into five pieces. Then we tool four inch strips of cardboard and used the krazy glue to stick two strips on the back of each piece of plastic. We took the four inch dowels and glued them to the back of the four inch strips of cardboard. We then took two inch pieces of cardboard and glued them, using the krazy glue, to the wooden circle. We the used the crazy glue to glue the dowels attached to the plastic blades, to the circle of wood.
View B
Step four: Then we used one of the drill bits to physical make the hole. Then we filled the hole with the crazy glue and stuck it onto the brass rod. Depending upon the glue you use, the amount of time you will have to hold and apply pressure will differ. We then glued cardboard to the base of the PVC pipe that is vertical. Then we grabbed velcrostripes, attached one to the bottom of the box and one to the cardboard that was glued to the pipe. We then stuck those together.
D.) Overall Wind Turbine
Section 3: Results
How much voltage and/or current did you generate?
- We generated 0.002 A of current.
Were you able to light a lightbulb? Why or why not?
- We were not because you'd need 0.03A to light a lightbulb.
Video of Our Wind Turbine
Section 4: Discussion
The Factors that Influenced the Amount of Voltage Induced
1.) The shape of the blades: Depending upon the shape, they can will harness more of the wind that'll turn the blades faster. In turn, it would turn the magnets faster. The faster the magnets move the more voltage that'll be induced.
2.) The length of the wire: The longer the wire is, the more resistance it'll have. This is because of ohm's law which states that, " I= V/R." So the greater the resistance, the lower current.
3.) The weight of the magnets: The heavier the magnet is, the greater the force of the wind would have to be. The heavier the magnets are, the slower they will spin. The slower they spin, they will cause less of a change in the magnetic field in the loops of wire. This means less current will be generated.
What Worked
- Using the strips of cardboard to connect the dowels to the blades and to the circle of wood, which made it easier to stick to the plastic and the flat circle of wood.
- Using a button with a hand drilled hole to connect the dowel to the circle of wood, which made it sturdy.
- Using rubber washers to reduce the friction between the brass rod and the cardboard box.
- Using PVC as our base, which made it sturdier.
- Using the velcro, which allowed us to take off the generator to make adjustments if needed.
- Using a box as our generator, allowed us to easily wrap the wire and have it keep its shape.
- Pulling the end of the brass dowel with the blades, closer to the generator. This brought it closer to the center of mass.
What Didn't Work
- Using a horizontal instead of a vertical wind turbine design. The horizontal design work best for winds at a higher elevation. The fans on the tables blew wind at a lower elevation. This made our design barely turn, since we were expecting the elevation of the fan to be greater.
- Using big rectangular magnets because the weight was just too heavy in comparison to the force of the wind. This made it harder for the wind, that the blades did harness, to turn the brass dowel.
The Various Things We Tried (that didn't work)
- We tried to use a wooden dowel, but switched to a brass dowel. This was because the wooden was heaver than the thin brass dowel. The downside was that the Brass dowel bent easier than the wooden one.
- We tried to use plastic folders from Ingles as the blades, but they were too thin and flimsy. When we put them in front of a fan, they just bent straight back.
- We tried to attach lug nuts to the end of three inch wooden dowels that would've connected to the large wooden dowel. This made it very heavy (hard to turn and stay straight). We tried to use duct tape and straws in between the dowels, but they just got heavier. In addition, they didn't properly support the small dowels.
- We tried to use the small magnets on our brass dowel, but when the number of magnet pairs were even then there was an even number of north and south poles. Therefore, they just stuck together despite the large amount of glue.
Advice/Tips
1.) Use a vertical design for the wind turbine because the fan is low to the table, so the vertical turbine would be able to harness more wind.
2.) Use the small and light magnets Mrs. Lawrence provides. They are lighter and will cause less problems.
3.) If you want a sturdy base, use PVC pipes.
4.) If you want to stick two round (3D) objects together, then glue a piece of cardboard between them.
5. ) When using hobby or Krazy glue, less is more! Plus, read the directions.
6.) You want the blades to be light, use a plastic bottle.
7.) Focus on your generator box before you start anything else. Despite what you may think, the generator is the most important part. The blades are easy to adjust, the generator not as well.
What I'd Do Differently
- Use a vertical design
- Use the small magnets provided
- Use a bottle with slits in the side that are pulled out
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