Find the Best Pinwheel Design
Wind energy is becoming more and more popular across the United States, maybe you’ve even seen a wind farm close to where you live! In 2015, approximately 7% of the electricity used in the U.S. was generated by wind – so who knows, when you switch on a light bulb in your house, that light might be coming from wind energy!
Wind energy is generated by wind turbines. These machines can look like giant pinwheels, and their job is to turn energy from the wind into mechanical or electrical energy. Believe it or not, the wind turbines we use today are based on designs that are over 4,000 years old!
In this activity we’ll be exploring different turbine designs by testing pinwheels, and learning about the factors that can improve their performance.
This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,200 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.
Wind turbines convert wind energy into mechanical or electrical energy. One type of wind turbine, the windmill, has been used all over the world for thousands of years to convert wind energy into mechanical energy, for tasks such as grinding grain and moving water. More recently, wind farms that use wind turbines to convert wind energy into electrical energy have become increasingly popular. In some states, wind energy is quickly becoming a major source of electrical energy. For example, in 2015 more than 30% of the electricity used in Iowa came from wind energy!
In general, wind turbines all have the same basic components; blades, a rotor and a shaft that are both turned by the wind hitting the rotor blades. To make wind energy as efficient as possible, engineers have experimented with many different wind turbine designs. For example, wind turbines can rotate on a horizontal or vertical axis, have large or small blades, and in some cases, they can even be bladeless!
Variations in the design of wind turbines are based on where the turbine will be located, and how environmental factors will affect its performance. However, the goal is always to maximize the amount of energy extracted from the wind. In this activity you will explore one of these factors, the shape of the blades, to determine how they affect the efficiency of your pinwheel.
WARNING: This activity requires handling sharp materials, please ask an adult to help you with these steps!
Extra: Experiment with other pinwheel designs. Observe which factors seem the most important for creating the best pinwheel.
Observations and Results
In this activity you designed and tested 3 different model pinwheels. Each design you tested had differently shaped rotor blades.
You should have found that the first pinwheel, with the folded over blades, rotated the fastest and most smoothly when placed in front of a fan or in a breeze. The triangle and rectangle shaped blades probably did not spin as quickly or as efficiently as the first one you tested.
The difference in performance of each pinwheel was the result of the different shaped rotor blades that you tested. The first pinwheel’s blade design allowed each blade to capture the most air as it rotated. To understand why this made it move faster, imagine a swimmer, racing through the water. With each stroke, a good swimmer will keep their hand closed and slightly cupped, to try to capture the most water in their hand. This allows the swimmer to ‘push’ against more water, and propel themselves forward. You can imagine if they spread their fingers and allowed the water to flow through, they wouldn’t be able to push themselves through the water as quickly.
Your first pinwheel design is based on the same principles. Because it’s folded over, it acts like a pocket for collecting air. The more air it can collect, the more efficiently it will be pushed around the rod. The other two pinwheel designs did not collect air in the same way. The wind moved past their blades without ‘bumping into’ the blades, therefore they weren’t pushed as quickly or smoothly as the first design.
Now that you know the basics of pinwheel rotor blade design, try experimenting on your own to make the most efficient pinwheel you can!
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Megan Arnett, PhD, Science Buddies
Science Buddies |
Wind energy, mechanical energy, electrical energy, wind turbines
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