September - December | 2015

This was a group project for E26, 3D Modeling. Our task was broken into two major components. We had to design wind turbine blades that maximized efficiency. Then, we had to design the wind turbine tower that minimized stress under different uniaxial load conditions. Our models would be 3D printed out of ABS, and tested using a air blower and tested with weights tethered backwards.

For logistics, I was selected as the team captain, as a final organizer and checker as well as planner for weekly meetings and status updates.

To begin, we each individually researched the different airfoil profiles in the NACA and UIUC airfoil database. A teammate simulated performance in Xfoil and we selected the Althaus AH 93-W-145 for our turbine. We decided that our turbine would have 3 blades since it has been shown experimentally that 3 blades have the best performance to cost ratio. The airfoil profile was then imported into SolidWorks, and we designed our actual blades to have a constant taper and constant scale down. A major challenge we faced here was accounting for the minimum filament print size of the 3D printer. This required slight manipulation in our scaling.

The next major step was designing a turbine tower. I suggested that since we knew the stress and deflection of the tower would be measured by a uniaxial test of attaching weights that pull on the back, we design a tear drop shape that maximized stiffness forward and backwards. While I knew that this would never be used in real life due to forces in all directions from wind, I reasoned that for the purposes of this class, my design would prove stiffer. The tear drop was then linearly scaled down all the way to the top. The major challenge for the wind turbine was a material constraint. Our project was to take no more than 20 cubic inches of material. We decided to hollow out the interior of the tower and break it into two components for easier printing.

Fortunately, our design proved simple to print and assemble. The clearance between the two tower components was sufficient and fit snuggly with the required glue. Moreover, our design for the turbine blades accounted very well for the limitation of the printer since it was printed very smoothly with no isolated filament lines.

Based on the metrics of performance, our project was a success. We achieved the highest power rating in the class of 2W at 565 mA. With regards to stress testing, we had a nearly linear displacement to weight. Given that the material was plastic, this kind of behavior was promising. Attached are some photos of our team and design.