Wind Turbine Project

thingiverse

This is a derivation of the OpenSCAD project submitted by Matt Larson. It was a project done by a high school physics class investigating the factors that affect the power generated by a wind turbine. This was the first full class 3D printing project I did. I made a couple very minor changes to the OpenSCAD file to make the variable names more intuitive for my students. I also added some clarifying comments where I thought they would help and cleaned up some Depreciated code. Print Settings Printer Brand: MakerBot Printer: MakerBot Replicator 1 Rafts: Doesn't Matter Supports: No Resolution: 0.3 Infill: 0% Notes: You may need to add a raft for some designs to keep them from falling over. If your machine can do a brim, this would also help. We used 2 perimeters on our turbine blades. Post-Printing Clean off the flat rectangle. We used a steady hand and razor blades. We found you had to shave the bottom corners of the base off to fit easily into the hubs. Be very careful as the turbine blades break easily. You could print with more perimeters to increase strength, but then you risk them being too heavy to get turning. How I Designed This This was made in OpenSCAD from a design originally submitted by Matt Larson. Each of my two physics classes picked two parameters to vary. We ended up with: Length Width Angle – Which was really twist “Fat Point” – Ratio of top length to bottom length We created 5 different versions for each parameter. I let the students decide what they wanted to set the parameters to as long as the blade was not absurd. Standards NGSS Overview and Background A few years ago, I bought a MakerBot Replicator 1. It was a project done by my high school physics class investigating the factors that affect the power generated by a wind turbine. This was the first full class 3D printing project I did. Lesson Plan and Activity Introduce the project and show students OpenSCAD. Show them how to change the variables and render the model. Allow students to play so they can determine what each variable does. Have student groups each identify one factor to change, while holding others constant. Note, this might mean two variables must be changed. Changing the "bottom_height" without changing "top_height" would change the total blade length as well. Students might change the ratio of top and bottom heights but keep length constant. Student groups share what they want to change with the class for discussion and input. Students create 5 different states varying their factor of choice. See my picture above where the "fat point" (or ratio of top to bottom) is changed while all other factors were kept constant. Print. It took my printer 3-4 hours to print a full set of blades, That is 3 each or your 5 different designs. Clean and mount blades in the hubs. Student groups test their blades 8.1 Method One: Press fit the shaft of a small hobby motor into the hole on the hub. Attach the motor leads to a volt meter. Position 20 cm in front of a box fan set to high. Read voltage. 8.2 Method Two: Mount blade on a straightened a paperclip. Position 20 cm in front of a box fan set to high. Use a Vernier or Pasco photogate to measure the spin rate. Students create a graph for their data and fit an equation using the regression function on their calculators. Students share data, graphs, and mathematical models with the class. Student groups use all of the data to design the "optimal" wind turbine blade Print and test final blades Duration Day one: Steps 1-5 above. Print over night Day two: Clean and mount blades (step 7). Takes longer than you think. Day three: Steps 8-9 Day four: Steps 10-11 Print over night: Day five: Test and crown the winner! Materials Needed Student Skills: Know how to make an x-y scatter plot Know how to use the regression function on their calculators Know how to analyze graph data Stuff needed Box Fan Test Equipment (dc hobby motor+volt meter or photogate) Some way to mount. I used a ring stand and attachments found in chemistry room Rubric and Assessment I looked only at the finished, optimized blade design. Some students ignored the data and created a design based upon what they thought would make a good design. As you might guess, these did very poorly. The groups that did the best used all of the data collected and changed each of the variables. This became a great teachable moment.