Tubercle Power: Whale Inspired Wind Turbine

I have a passion for renewable energy and the different ways of producing it. My uncle is aware of my passion and suggested that I watch this documentary. The documentary talked about adding tubercles onto airfoils, I was inspired and I knew I had to test it for myself.

I wondered what effect tubercles had on the leading edge of wind turbine blades. I hypothesized that if tubercles increased the lift and reduced the drag on an airfoil, then the tubercles would make the wind turbine more efficient and generate more power. According to my research, tubercles can increase the efficiency of an airfoil in the range of 15-20%.

My project has potential to make the world a better place by benefiting the renewable energy industry. By improving existing wind turbine technologies, my project can help us work towards a more sustainable future.

*This project is a continuation project I presented last year at the regional level. Since then I have made many improvements and conducted many more experiments to further my research on this topic and improve the accuracy of my results. As I go on to explain my project in the next sections, I will state what I did last year as it is important in understanding how I improved my methods of research this year.

Design process:

Last year, I designed and 3D printed 3 sets of tubercle modified blades, each one having different sizes and amounts of tubercles. I also printed a set with no tubercles. I constructed a base from plumbing pipes, a microphone stand and a DC motor. I made one for each set of blades.

This year, I realized that not all of the turbines were constructed equally. For example, the holes I drilled inside of the hubs were not all centered, giving me inaccurate results. I fixed this by only swapping the blades instead.

Testing procedure:

Physical testing:

Last year while testing, I only tested each turbine once, this was not a good way to produce accurate results. This year, I ran each trial 5 times on each set of blades. I performed many different tests on the blades, but I will explain one.

The blade sets were all tested separately in a controlled environment. They were placed in front of a large fan with 3 wind speeds. I tested the power output of the turbines with a voltmeter. I developed a procedure where I would let the fan run on each speed for two minutes, as I video recorded the readings.

Wind Tunnel:

I could see which blades were working better, but I wanted to be able to visualize the airflow over the blades. My first approach was to build an entire wind tunnel. Unfortunately, it did not work as well as I had hoped, so I had to resort to a different approach.

Computational Fluid Dynamics (CFD) Software:

I had never used any program like this before and I struggled a lot to get it to work. But eventually, with some help from my cousin, I was able to figure out how to run the simulations.

Physical testing results:

Through the test that I described in the "how" section, I concluded that the blades that were modified with small tubercles worked the best, the medium tubercle blades came in second, then the original blades were third and the blades that performed the worst were the large tubercle blades.

I came about my conclusion by logging every ten seconds from the footage I recorded in excel. I logged each of the 5 trials from each turbine and I took the average of the voltage generated at each windspeed. I then took the average from all five trials.

I then compared the efficiency of the tubercle modified blades to the original blades. The small tubercle blades were 8.22% more efficient than the original blades and the medium tubercle blades were 5.88% more efficient than the originals. The original blades were 5.82% more efficient than the large tubercle blades.

Last year, after only testing each model once, I concluded that all of the tubercle modified blades were more efficient than the original blades in the range of 15-20%. I believe I had greater results last year because the hub of the original blades was crooked, giving it a disadvantage. This year, I tested everything as equally as I possibly could.

Even though 8% is less than 15%, It still proves that the tubercles increased the efficiency of a wind turbine by a significant amount. My tubercle modified blades did not perform as well as they were supposed to (according to my background research). I believe this was due to TinkerCAD, the website I used to design my blades. I was only able to add more material onto the existing blade model and I could not remove material from it. As a result I had a bumpy design instead of a wavy design. I think that the blades would have yielded better results if they had a wavier design.

ANSYS results:

Unfortunately, I was unable to import and simulate my turbine blades in ANSYS, so instead I created two basic airfoils, one with tubercles and one without tubercles. This means that my results were not very accurate for the simulation of my wind turbines, but this is as close as I was able to get.

I tested the airfoils at different angles of attack (AoA) to see how the results differed.

The graphs generated by ANSYS showed that the tubercle modified airfoil was generating up to 22% more lift than the original airfoil while at a 30º AoA. I do not believe that my results are the most accurate as I do not have a profound knowledge of how ANSYS or complex aerodynamics work. However, I do believe that my results are enough to show that tubercles can increase the efficiency of an airfoil.

Conclusion:

My hypothesis was correct, tubercles do increase the efficiency of a wind turbine. Although tubercles can increase efficiency, the tubercles cannot be too large. Otherwise, they will be less efficient than blades with no tubercles at all. It seems that smaller tubercles work the best as they were 8.22% more efficient than the original blades. The blades with tubercles were also able to start up at lower windspeeds, meaning that they would be able to generate electricity on less windy days.

Although my results in ANSYS were probably not the most accurate, they did still support my hypothesis and aid in the understanding of the physics behind my results during the physical testing. I was able to learn a lot about running simulations and CFD though this experiment.

Why it matters:

My results are important as it shows us how we could move one step closer towards a more sustainable future. 8.22% might not seem like a lot at a small scale, as in my project, but it could make a big difference at a larger scale. It is estimated that all the wind turbines in the world generate close to 3,000 Terawatt-hours (TWh) of electricity annually. If all the wind turbine blades were replaced with tubercle modified blades, they would be able to produce an extra 246.6 TWh of electricity. A 246.6 TWh (terawatt-hour) annual energy supply would be capable of powering roughly 22 to 23 million average homes annually.

There are various ways that I would like to improve and extend my project. The software I used to modify my turbine blades was very simplistic and beginner friendly. That meant that I had many limitations while designing the blades. In the future I would like to explore more advanced software to design future models.

According to research, tubercles are supposed to reduce the noise produced by an airfoil. I think that it would be interesting to test and analyze the acoustic properties using ANSYS.

I would like to acknowledge all the people who helped make this project possible.

A special thanks to Chris Gryzbowski for inspiring my idea.

Thank you to my teacher, Mr. Brian Burns for his attempt with 3D printing. As well as Mason Dallas from 3D Printing Room who assisted with the printing the 3D blades.

I would also like to thank my cousin David Morena for help with ANSYS, the CFD program

Lastly, I would like to thank my parents for their continued support financially and creativity.

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