Wind Turbines

The Wind Turbines activity was designed as part of Designing Green with Olin College Engineering Discovery! It is targeted at elementary school children.

Goal

Through an iterative design and testing process, students will discover the optimal fin number, shape, size, and angle to make their wind turbine produce the most energy.

Materials

The following materials are necessary:

  • 1/2 gallon milk carton
  • 1/4 inch or smaller wooden dowel
  • Drinking straw
  • Styrofoam block or circle, 1-2cm thick, 3-5cm in diameter
  • Construction paper for fin design
  • 2 feet string
  • Dixie cup (2 oz)
  • Pennies or some equivalent weight
  • Duct tape
  • Scissors
  • Pencils
  • worksheets
  • Fan

Preparation for Activity

Build bases for the wind turbines, using the following instructions. Make one per student.

  1. Cut off and dispose of the top triangular portion of the carton
  2. Punch two holes the size of the drinking straw across from one another near the top of the carton
  3. Push the straw through these holes across the top of the carton
  4. Slide the dowel through the straw - it should be allowed to spin freely
  5. Attach the string to one end of the dowel with duct tape such that it can wind up as the dowel spins
  6. Center the Styrofoam block to the other end of the dowel - this is where fins will be attached
  7. Attach a paper cup to the end of the string not attached to the dowel

Discussion

  1. What are major sources of power in your home?
    1. Coal, Natural gas, petroleum
  2. What are the good and bad things about these resources?
    1. Good: heat, appliances, computers
    2. Bad: non-renewable, pollution
  3. Who knows some examples of renewable resources?
    1. Solar, hydroelectric, wood, geothermal, WIND
  4. Definitions
    1. Force - a powerful effect of influence - a push
    2. Energy - the amount of work that can be performed by a force
    3. Work - the amount of force needed to move an object some distance
    4. Power - the rate of doing work - how fast an object is moved
  5. Energy conversion from wind into something usable
    1. Wind pushes fins, causes them to spin on an axis - the faster wind (force) the more work is put on the wind turbine, and therefore there is more energy which can produce more power
    2. Power from the turbine can then be passed through wires to power homes and businesses
  6. Why are wind turbines a good option?
    1. Renewable, no pollution, very small environmental impact
  7. Limitations?
    1. Need consistent source of wind!
  8. We are going to be designing the fins for a wind turbine - why?
    1. They are what the wind hits and what makes it spin
  9. WRITE GOAL ON THE BOARD - explain

Protocol

  1. Break students into small groups - each group needs an instructor
  2. Give each student a wind turbine base for size reference - not construction paper!
  3. Explain how we will measure power
    1. When the turbine spins, the string will wind up and lift the cup full of weight - the more weight the turbine can lift, the more power it is producing!
  4. Give each student a worksheet - work through this with each individual - MAKE THEM THINK ABOUT THESE THINGS AND EXPLAIN THEM!
    1. Fill out number of fins and write down why
    2. Be sure they think about making it too heavy with too many fins, balancing the fins around an axis, and having enough fins to actually produce energy
    3. Have students draw what they think a good fin shape would be and write down why they are making it that shape and size
    4. Be sure students write down their reasons
  5. Once fin design and number has been approved, give them a piece of construction paper - allow them to carefully draw their fin design once
    1. Have them trace the remaining fins needed from the first template
  6. Give students as many small dowels as fins, help them duct tape fins on and space fins on the axis
  7. Ask students about the angle of their fins - what is best!
    1. Consider direction of wind!
    2. Important that they are all slightly angled in the same direction
  8. TEST IT OUT!
    1. Try it without pennies first
    2. If it doesn't work, ask student why, and if they can make any immediate changes let them do it.
    3. Try adding pennies in small quantities - challenge them to maximize the power their turbine exerts!
    4. If it works, ask student how they can change their fins to make them better
  9. Repeat 4 - 8 as many times as they can

Conclusions

  1. What is the best number of fins?
    1. 3-4 is typically best - not too heavy, but can produce energy
  2. What is important about the size of a fin?
    1. It must be large enough to catch the wind, but not too heavy
  3. What types of shapes are good for fins?
  4. Why is the angle of the fins important? What is best?
    1. All angled 30-45 degrees in the same direction - catch wind consistently and push the turbine around