Instructions: Coffee Cup Turbine
By: David Willis, Associate Professor, University of Massachusetts Lowell
This work was supported by a grant from the Massachusetts Clean Energy Center (MassCEC). The materials presented do not necessarily reflect the opinions of the MassCEC.
We are grateful the MassCEC for their support and encourage you to look at some of their online resources.
Before Starting: Read and understand how to do this activity safely
á Be sure to have an adult help you when cutting parts.
á When testing your turbine, be sure to wear safety glasses
á When testing your turbine, make sure the spinning blades are far away from your face/your body
Constructing your wind turbine tower and nacelle
á Collect the following items:
o 1 x Long piece of 1Ó PVC pipe (~18 inches long).
o 1 x Short piece of 1Ó PVC pipe (~2-6 inches long).
o 1 x PVC 1Ó TEE fitting
o 1 x PVC 1Ó Pipe Coupler fitting
á Push the shorter and longer PVC pipes into the TEE fitting as shown below.
á Push the pipe coupler fitting onto the end of the short PVC pipe as shown.
You now have your wind turbine Tower and Nacelle!
Assembling your wind turbine rotor and generator.
á Collect the following items:
o 1 x Roll of Duct Tape (or any other tape you may have)
o 1 x DC generator (http://www.vernier.com/products/kidwind/wind-energy/kw-gen/)
o 1 x wind turbine hub (note: we will show you how to make a hub later in this instruction manual) (http://www.vernier.com/products/kidwind/wind-energy/kw-wth3/)
o 3 x wooden dowels or 3 x wooden pencils.
á Connect the generator to your hub.
á Loosen the screw knob on the hub
á Insert the dowels into the hub and tighten the screw knob.
á Take a strip of duct tape and wrap it around the generator. This will ensure a tight fit between the generator and the nacelle.
Your wind turbine rotor, generator and hub are assembled!
Installing the generator on the tower in the nacelle
á In this step you will install the generator in the nacelle/hub of your wind turbine tower. There are a few steps:
o Start by removing the short PVC pipe from the TEE fitting
o Next, pass the red and black wires into the pipe, through the TEE fitting. These wires will carry the electricity out of your turbine generator.
o Carefully press the generator into the PVC coupler fitting. Increase/decrease the amount of tape wrapped around the motor to ensure a snug installation.
á Reassemble the PVC tower (press the TEE fitting together again)
á Add some strips of tape to attach the wires to the tower.
You are now ready to go and design some wind turbine blades. The turbine is almost done.
Designing your blades
á Now we will explore the blade design process. For this we will use a simple, 20oz Coffee Cup. Once you have built one set of blades, you can try any number of modifications to improve your wind turbine performance.
á Collect the following parts/equipment:
o 1 x Safe Scissors (be sure to ask an adult to help you use the scissors)
o 1 x cardboard coffee cup
o Some clear tape or glue stick
o The blade design template (see below this step), or click here for a PDF.
á Once you have all the equipment/parts cut out the wind turbine blade templates.
á Once you cut out the wind turbine blades, you will use them as templates for the actual blades. To do this, you should stick the paper templates on your cup.
o Hint: Keep the printed writing facing you when you tape the template on the cup.
o Hint: Put the root of the blade into the lip of the cup (where it says Òlip of cupÓ).
Cutting and mounting your blades
á With an adult, use the scissors to carefully cut out the blade shape. You should have 3 nearly identical blades if you do this correctly:
Notice: Your blades are curved and twisted. If you try different blade shapes and designs, they will likely perform differently. A challenge for you is to find what you think are the best blade shapes.
á Use duct tape to mount the blades on the rotor wooden dowels. Make sure the blades are all facing the same way. (Hint: The part of the coffee cup that was Òinside the cupÓ should face toward the wind).
Now you should have a working turbine. Start by trying different blade angles and seeing how that affects your design.
Making your own COFFEE CUP HUB
If you donÕt have a KidWind Turbine Hub, you can make your own using the bottom of the coffee cup you used to make your turbine blades.
á Have an adult help you to carefully cut the bottom of the cup off.
á Once you have cut the bottom of the cup off, you should measure and mark the locations where the blades will be installed.
o If you have 3 blades we recommend first finding the center of the cup and then marking 3 x locations on the outide of the cup that are each separated by 120 degrees.
á At each of the locations that you plan to install a blade, cut a Vee-shaped cut or notch carefully using your scissors. We find that it is best to make these notches on the very bottom of the cup. These notches should be big enough to allow the wooden dowels/pencils to sit in.
á Place the blades into the notches as shown below (left). Carefully, using small strips of duct tape, secure the blades onto the coffee cup hub.
Next you need to attach the hub to the generator. Depending one what type of generator you have, you may need to get creative. In this example a pulley that is designed for this motor is used. This pulley is duct-taped to the hub in the center (if you donÕt get the center, your turbine will likely wobble).
You may consider using glue, chewed gum or some other creative approach. Talk with some adults to figure out a way to attach the hub to the generator if you canÕt come up with a solution.
Once your hub is complete, put the hub onto the generator.
You are all done. Go and test your wind turbine now!
Hints for making better blades
One of the nice things about the coffee cup turbine is that it is very cheap and easy to make and test new blades. Some of the design parameters you may want to explore are:
á The overall blade pitch angle: The angle of the whole blade in the hub is an important parameter in the performance and design of wind turbines. Consider that many wind turbines have variable pitch blades so that they can adjust this angle for different wind conditions. Try out some different pitch angles and assess how this affects your wind turbine performance!
á The chord of the blade: How ÒwideÓ the blade is. You see that many real world turbines have much smaller chords than their length. Is this advantageous in your turbine?
á The blade taper: The taper is a measure of how quickly the blade chord changes as you go from the hub to the tip of the blade. Take a look at some photos of actual turbines to determine some tapers you might like to try.
á The blade sweep angle: The angle the blade makes on the cup affects the amount of twist the blade experiences from root to tip. The twist is on of THE MOST important parameters in fundamental wind turbine aerodynamics. Try different cup cut angles and see how your turbine performs differently. You may find that the turbine spins faster and slower. You may also want to use a protractor to determine the angle at the blade hub vs. the tip to figure out the amount the blade twists.
Be sure to visit KIDWIND online (https://www.kidwind.org) to get other ideas and tips on how to improve your design.