Aaron Cantrell
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This was a project for my Appropriate Technology class. I chose to focus on small scale electricity generation and was interested in micro-hydroelectric systems. After talking with a few professors I was enticed by the flexibility of Banki turbines and decided to fabricate a modular one so we could easily change parts out as needed during testing and experimentation. The Banki turbine is sort of a turbine/water wheel hybrid that is significantly more efficient than water wheels and doesn't require the higher pressure that most turbines need to work efficiently. My partner in the class found a few papers outlining the calculations for optimal curvature, dimensions, etc. for a given flow rate and we back calculated to find a good medium for our testing purposes. When I designed the turbine, my intention was to stick with a highly modular design that would allow us to change variables as we needed during testing if something wasn't working as expected. Surprisingly the most tedious parts to fabricate were the red fins. We made them out of ABS, baking them in an oven at precisely controlled temperature and time as we noted that contraction about the length of the fin and expansion along the width occurred during heating. I machined the PVC disks on a CNC mill and turned the aluminum flanges on a lathe. I decided to recess the nuts on the inside of the disks to create a lower profile for less flow resistance during use (we decided that external access to the screws was a better idea then tapping the flanges and bolting from the inside of the turbine).

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