Wind Turbine and Energy Lesson: the Answer Is Blowing in the Wind

In this middle school classroom activity students explore wind turbine basics and turbine blade design. Students work through iterative testing of their prototypes. They calculate electricity generation as well as rpm of the blades to determine their model's productivity.

There are expectations of 3-D modelling in Tinkercad for blade designs and the option of creating pulleys and gears. Depending on your state and region there might also be possibilities for local and state competitions through KidWind.

As a STEM project, the turbines address science (energy conversion & physics of aerodynamics), technology (rpm assessment through digital analysis & 3-D modelling), engineering (prototyping multiple designs) and math (calculating angular velocity). Out of all the projects in my STEM class, this project truly exemplifies the engineering and design cycle.

1.) Cardboard of various thicknesses (I start stockpiling at the beginning of the school year)

2.) Turbine blade materials (thin cardboard, cardstock, foam board, thin styrofoam thick plastics, balsa wood)

3.) Hot glue guns (1 per class group)

4.) Hot glue sticks (2 lb for 100 students)

5.) Scissors (1 per class group)

6.) Utility knives (1 per class group)

7.) Cutting pads for utility blades ( I use large vinyl tiles- cheaper & sturdier than cutting mats)

8.) KidWind turbine hub (to hold the dowels which hold the blades)

9.) KidWind turbine generator with wires (to analyze voltage output)

0.) 1/4 " dowels (to hold blade and insert into the hub; 12 per class group)

a.) Kid Wind 1/4" dowel 5" long

b.) 1/4" dowels 6" long

11.) Multimeter with alligator clips (to measure mV & mA)

12.) KidWind Blade Pitch Protractor (best device to measure blade angle on the hub)

13.) Fan

Optional:

KidWind gear font (if you don't want to 3-D print gears)

Long rubber bands (for pulley belts)

0.125" metal dowels (for connect the hub to gears or pulleys)

straws (used as a bearing for the 0.125 metal dowels so you can attach it to the tower)

KidWind starter pack includes hub, generator and 25 dowels

Go Direct Energy Sensor (advanced alternative to measure mV & mA)

Digital anemometer (to help find the ideal location/ height of your model in front of the fan)

Teacher Resources:

William Kamkwamba site (The Boy Who Harnessed the Wind- an amazing story of a young boy's ingenuity using wind)

William Kamkwamba TedTalk

KidWInd Windwise curriculum (great resource for presentations, design ideas, debates and extensions)

Science & Engineering Standards:

Next Generation Science Standards: (Middle School)

MS.Engineering Design

MS-ETS1-1.Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.

MS-ETS1-2.Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.

MS-ETS1-3.Analyze data from tests to determine similarities and differences among several design solutions to identify the best characteristics of each that can be combined into a new solution to better meet the criteria for success.

MS-ETS1-4.Develop a model to generate data for iterative testing and modification of a proposed object, tool, or process such that an optimal design can be achieved.

How the Project is Introduced to the Students

1.) Our students have had some previous background knowledge on renewable energy and electromagnetism. The PowerPoint Supplement under the WindWise Intro is a great start to create your own- directed introduction.

Attached below is the grading I use for the project and a modified version of the slideshow through WindWise.

1.) In their Engineering Journal, students draw their preliminary idea for their tower and an idea for their first blade prototype. Students are expected to research online for blade and tower design concepts.

2.) The tower must stay within a set area on the test table. The defined area is so students don't build their tower directly in front of the fan. Everyone has a standard distance set back from the fan.

3.) Students must also note the height of the center of the fan off the surface of the table (2 feet). This standard is based on the height of the center of the fans if students were to compete at the local KidWind Challenge. (more on that later...)

4.) I go over their designs & they post the design to Google Classroom. I have each student make the design to avoid the possibility of the "my partner is not here and I don't know what I'm doing" scenario.

1.) Students build the tower for the turbine.

2.) To standardize the fan height I prop the box fan so the center is at 2 feet per the KidWind Challenge fan set- up.

3.) To know the ideal height we use the anemometer to find where the wind speed is the fastest.

4.) To protect the generators from being heavily glued to the tower, I have students use our 3-D printed generator clip.

5.) To save time on this project you could have pre- built towers and only have the students navigate the blade concept.

1.) Students start on their individual blade prototypes. I have them not hot glue the blades to the dowels, or just use a few spots of glue. It's easier to change out the blades on the dowels with a light glue load.

2.) Students will design 1 blade prototype on Tinkercad. While those are printing they will design other prototypes with other assorted materials.

3.) Students will test out the blades after the towers have been built and their generator is attached to the tower.

1.) Students will all start out working with a direct drive turbine.

2.) Some students will wonder how they can increase their energy output and this would lead to the discussion of gear ratios. I have students research and then explain how a gear ratio could improve the output. Once they have explained the concept to me I will explain how they could do this with their materials.

3.) There is a selection of gears, pulleys and pulley belts offered in class as well.

4.) I've created an adaptor to fit on the hub. Axles will insert into a hole of the hub.

5.) The axles will have a straw sleeve to act as a bearing so it can rotate. On the opposite end of the axle it is attached to a gear or pulley. The axles I use have a diameter of 0.125" or 3.2 mm.

6.) On the generator is a gear or pulley. The hole diameter to fit the generator spindle is 3.14 mm.

7.) The challenge students will find is how to mesh the gear teeth without slipping or how to connect the pulley system without the belt slipping.

8.) Students who want a larger pulley or gear will use Tinkercad to develop their own gear and pulley sets.

....

For a shortcut to make gears we use Thingiverse Customizer (create STL files):

https://www.thingiverse.com/apps/customizer/run?thing_id=1516585

For a shortcut to make pulleys we use Thingiverse Customizer (create STL files)

https://www.thingiverse.com/apps/customizer/run?thing_id=175044

1.) Students will describe the variables of each of their blade prototypes. They will also measure the mV and mA of their prototypes, ultimately to solve for mW.

2.) There are a variety of factors which could affect their energy output. Students will record all of the following:

• blade material used
• number of blades
• pitch of blades (use the KidWind blade pitch protractor)
• area of blades (use graph paper to outline the area or a geometric formula for a simple shape ex. trapezoid).

3) Once the 4 (I have them make more) blade configurations is created they will enter the data in the data table. See attached document.

Attached below is the document I use for recording the data.

Once students have found their best blade design they will analyze the rpm.

How to Set up Your Turbine to Test RPM

1. Place a marker (large colored mark or different- colored blade) on one of the blades.

2.Have someone hold a large piece of cardboard behind the tower (not too close) to make the blades easier to see.

 3. Record your video for 4 seconds using PhotoBooth on your LAPTOP (your phone video recording doesn't work) to get a .mov file.

4. Share the video (airdrop or e-mail) with your partner.

Each partner will assess the data on their own to find the RPM average for Data Table 2.

How to Use Tracker Online to Determine RPM (Also refer to the attached video tutorial)

Tracker online software link here

Written  Directions on How to Use Tracker Online to Determine RPM

1)   Click this link to go to Tracker Online.

2) Open Tracker.

3)  Go to File > Import > Video.

4) Select Choose File (choose your video from your laptop) > Load. 

5) Select Track > New > Measuring Tools > Protractor.

6) Run the movie clip to see which direction the blades turn (Forward green button on the bottom left of the window).

7) Drag the protractor to the center of the hub. Find the green sticker or the trailing edge of a blade profile. Move the green measuring line and the "0" degrees to the starting point and overlapping each other. 

8) Find the time at that time frame in seconds. This is located in the bottom right data table window under  t (s). This is the "initial time" of the still image. Enter this in Data Table 2.

[1st frame= 5.334 s for this example]

9) Select the advance frame button and  skip ahead at least 2  frames.

10) Drag the green ray lines to line up new location of the sticker or trailing edge of the blade.  

11) Find the 2nd time frame and angle from the 1st to the 2nd still image. In the lower right data window, enter the new time "t" in the 2nd frame time in your Data Table 2 and the angle in your Data table 2.

[2nd frame= 5.434 s ... for this example]

[angle= 117.8 degrees ... for this example]

12) Calculate the time difference.

[time difference= 5.434 s- 5.334 s= 0.110 s ... for this example]

13) Determine the rotations (angle divided by 360).

[rotations= 117.8 degrees/(360 degrees in 1 rotation) = 0. 33 rotations ... for this example]

14) Determine the rotations per second (rotation divided by the time difference between the 1st & 2nd frames) .

[0.33 rotations/0.110 s = 3.00 rotations/s ... for this example]

15) Determine the rotations per minute (rotation per second multiplied by 60) .

[(3.00 rotations/s) (60 s/min) = 180 rotations/ min ... for this example]

16) To do the next time segment drag the ray lines together or enter "0" in the angle box to reset the protractor and repeat steps #8-16.

17) Determine the average of all the calculated rotations per minute of your turbine.

1.) Students create a slideshow on important features of their project as their assessment.

2) They discuss the aspects of their blade prototypes which worked well, how their tower fared and an explanation on two topics about wind energy.

3.) This presentation is similar to what the judges would ask the students to present at the KidWind Challenge.

Attached below is the rubric for the design documentation.

We are fortunate to have a local educator start up a KidWind competition in our home state. This is a national competition and the top three wind turbines at the state level get invited to enter the national competition. It's a great way to end the unit for those with a competitive edge. KidWind can expand into other states and if you contact the organization, they will help you establish a presence. KidWind also offers online and live workshops to run a program or competition site.