March 2021 - May 2021
WILDCAT WIND POWER BRAKE DESIGN
During my junior year at Kansas State University, COVID was in its peak. Almost all classes were exclusively online for the entire school year, and the University itself was limiting many in-person events (as were many other schools). Because of this, the Collegiate Wind Competition for the year was much more limited in scope than it had been in previous years, and the maximum wind speed we would be expected to test at (12 m/s) was much lower than in previous years (up to 20 m/s). Because of this lower wind speed, and the reduced ability to collaborate due to COVID, I was tasked with creating a fully mechanical, contained way to regulate RPM. After doing some research, I landed on the idea of creating a centrifugal brake. While centrifugal brakes are not a new idea, the implementation of putting it inside our wind turbine was. Specifically, there are 3 components: the connector, the shoe, and the drum (from inside to outside). The connector is designed to have a friction fit on a keyed shaft and simply translate rotation motion to the shoe. The shoe has portions of thin plastic that allows for it to stretch and expand when a certain RPM is reached, and make contact with the drum. The friction between the shoe and the drum is what allows this design to regulate RPM.
Why Create a Centrifugal Brake?
Initially, we needed a quick solution for RPM regulation as competition was nearing and what we had been doing previously (shorting the 3 phases of motor) hadn't been working. The centrifugal brake was the easiest way I saw to make a contained mechanical braking system.
Different iterations of our mechanical brake involved editing the equations I had built into the model (referencing all the critical dimensions of the brake) and automatically having the model rebuild itself with the new parameters. This allowed me to create many different prototypes and export them to .stl format rapidly, allowing for real world testing to see which design would fire off at the correct RPM we were looking for.
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Overall, this design was flawed in the fact that our end result was plastic on plastic friction to create a braking force. We experimented with different materials and coatings, but at the end of the day the brake's durability was usually shot within a minute of full windspeed operation. Nonetheless, the design is a good proof of concept and something to potentially revisit for a different application.
