update: 2nd design
- fixed a bug in sweep() and solved the problem of blade termination by introducing a wedge-shape. Hidden airfoil design is demonstrated in cross sectional view.
- added an airfoil-shaped 50 magnet ring to harvest electric energy. Stator coils will be fixed to bracket (not shown yet) after magnet delivery and 1st print.
- Intended practical uses: wind light, or charger. Sailing boat position light. Why not also harvest some river current with it?
Background and first design
Studying some logarithmic spirals I stumbeld over the Archimedes windmill patented and produced by a Rotterdam company called the Archimedes. Because I liked the idea behind it, I started to implement a first version to see it running, then a second version much closer to the original, because I also liked the design itself.
Obviously the company's windmill has blades made from metal sheets rolled around an axis and having no specifiic aerodynamic design. Although they claim an amazingly high efficiency for such a small wind turbine as well as a silent run, I suspected that a proper airfoil design might not be wrong - and also enhance the harmony and statics of the design.
So I started to implement a libary for NACA airfoil data and a sweeper to be able to seemlessly juggle around airfoils with changing parameters in 3D space on arbitrary trajectories.
Well, this thing is the outcome for now. I guess I also will add some terminal profile, but I haven't spent time on finding a good solution for this.
I added an STL file for direct printing. There I added a foot to stabilize the print. It is meant to be cut off after print to enhance aerodynamics. As shaft I use a 2mm bike spoke. I drill up the hole in the turbine (1.9-2mm drill bit) and heat the spoke before poking it in. The holes in the bracket I drilled up with 2.5mm. The bracket easily opens up 10mm to plug the turbine in.
bought 50 cylinder magnets DxH = 2x1mm to be glued into the ring.
The ring will be glued to the blades as shown in the design.