SCIENCE STUDENTS GET “BLOWN AWAY” IN ATDD WIND TUNNEL
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Wind turbine models in hand, the Wind Energy team from the Appalachian Regional Commission (ARC)/ORAU Science Academy visited the ATDD wind tunnel facility on July 20, 2017, to have their turbines tested.
The team was comprised of nine students from eight different Appalachia states. This is the seventh year ATDD has participated in this annual event.
The Wind Energy team was lead by Lauren Wilmoth, a STEM and Honors Biology teacher at Oak Ridge High School, and Mark Rubin, a middle school teacher from Maryland.
The students pictured below are:
Front row left-to-right
Celia Torres Lopez (VA), Belle Beckner (SC), Madyson Cahill (OH), James Click (WV), and Anthony Tipton (KY)
Back row left-to-right
Makenze Hurtubise (NY), Gavin Awtry (NC), Sidney Vass (TN), and Ziah Kennedy (NC)
Building a model Wind Turbine
The students started their week by doing some background research on the internet including using a wind energy virtual lab by 3M and visited the Buffalo Mountain Wind Farm located just north of Oak Ridge, Tennessee.
Each student built a platform base with PVC and attached the motors and gears. They spent a majority of their time fashioning the blades and trying to determine what would work best to produce the most energy. Lauren encouraged the students to “think outside the box” which produced quite unique blades. They worked with a variety of materials including balsa wood, corrugated plastic, and thin metals. Lauren demonstrated for the students the use of the ORAU 3-D printer to make the blades of her model.
At the beginning of the testing session, ATDD engineer Randy White briefed the students on how the wind tunnel functions. He explained that the ATDD wind tunnel is an “open return wind tunnel.” This means “it sucks the air essentially in from a big room” and exhausts it back out into the same room.
Randy then showed the students the test section, which is a one meter by one meter square area, the propeller anemometer which is the standard used for calibrations, and a device used to determine what speed of the airflow is in the wind tunnel. He then went on to discuss with them some of the instrumentation.
The ATDD wind tunnel is normally used to calibrate anemometers used at the Climate Reference Network sites. However, the students models were too tall to fit in the test section, so their turbines were placed inside a cage at the exhaust end of the tunnel. Randy constructed the cage especially for this annual event. It is an aluminum frame with soccer netting. The cage is necessary because these tests are often destructive and it protects observers outside the cage from flying debris. Randy also constructed the power gauge used to determine the output of the wind turbines.
Randy and ATDD researcher Ron Dobosy assisted the students with documenting the data and lead short discussions about the results, both successes and failures. Mark Rubin handled the models inside the cage. The tests were conducted at wind speeds from 3 to 15 meters/second (6.7 to 33.6 miles/hour).
“How did it go?”
Randy, Ron and Lauren were interviewed following the event about their perceptions and noteworthy occurrences.
Randy explained that “we don’t give them any restrictions on it. But the big ones are kind of disadvantaged because of the way our wind tunnel’s set up at the exhaust, they don’t get to fully utilize the full wind flow because there’s a big hub in the center that’s kind of a no flow zone. So when your propeller’s sitting there spinning, it’s going through some high wind speed and then almost zero wind speed. Whereas the ones (turbine blades) that are like a foot in diameter, they get to not have a dead zone. They get to experience the full air flow. So they’re at an advantage in the testing. But we didn’t give any feedback to regulate what they want their design to be.”
“I was surprised with one that was kind of designed like a, I thought it was a pepper or banana but they said it was a comma. It was one that performed well. So sometimes that was not obvious to me that it was going to perform well. … sometimes it’s interesting to get a different thought process than just trying to absolutely tweak a little bit, a previous design.”
Ron remarked that “the serious piece of it was that there were some blade designs that worked better at lower speeds, and other blades that worked better at higher speeds, and the ones that work well at high speeds barely start at the lower parts, and then, when they got up to the higher speed, they’d be generating away, happy as anything. Now, the other ones might do quite well at the low speeds, they wouldn’t generate as much as these faster moving ones later, but they would be operating well, and then they’d hit a maximum. Their blades would deform, and they’d fall apart.”
Lauren said “Because of the really high wind speeds we end up with blades being broken and thrown off in all different directions. The kids really enjoy seeing their inventions break. When we have designs that don’t break we encourage students to ask themselves, ‘Why are some blade designs more successful than others.'”
Back in the classroom the students examined the data and discussed the results.
The students all agreed that it was a very exciting experience and that they learned a great deal about the scientific and engineering processes involved in designing, researching, engineering, testing, and analyzing data.
You can read more about the 2017 ARC/ORAU Science Academy here.
You can check out the flickr album for more photos of the week long event.
The Wind Energy team gets a “feel” for the winds their turbines will have to endure
Lauren (left) assists Sidney with
putting together her stand
Mark explains how to attach the gears, motor
and blades to the support structure
Anthony adds shafts to his blades
Randy explains how the wind tunnel functions
Ziah and Ron note power levels while Mark (in the cage) holds onto the wind turbine
And the winners are:
Madyson had the best performance
in the classroom and
James reached the highest output in the wind tunnel reaching 49 mW (milli-watts) – enough to power a small white LED flashlight of about 6 “candle power”.