Academy aero lab researchers harness energy from ocean waves

  • Published
  • By John Van Winkle
  • Air Force Academy Public Affairs
U.S. AIR FORCE ACADEMY, Colo. (AFNS) --  Air Force Academy researchers have harnessed 99 percent of the energy in a simulated ocean wave and are preparing to take their emerging technology to the next level.

The energy research is part of a National Science Foundation-funded research project to create the world's first free-floating, fully submerged wave energy converter that generates electrical power from deep ocean waves.

Researchers in the Academy's Department of Aeronautics began this project in the fall of 2008. The department's professors have decades of experience researching feedback flow control and fluid dynamics for various military aircraft and NASA spacecraft, which is the rare and necessary expertise to create a successful wave energy converter.

The latest tests are experimental confirmation of the computational simulations which began the project.

"We had actually better than 99 percent wave cancellation and efficiency in those simulations," said Dr. Stefan Siegel, who is leading the research effort at the Academy.

"Now, everybody looks at simulations and says 'well you're making all those assumptions and deriving the equations,'" he said.  "The short of it is nobody believes simulations other than the guy who did it. So what we did over the last year here at the Academy is we set up a very small -- about 1:300 scale -- version of the deep ocean wave in the lab, we built a wave tank, and we built a scale model of our wave energy converter that we will use in the open ocean.

"What came out of those initial experiments is that we were able to get 95 percent of the wave's energy," he said. "That is in sense confirming and replicating the results that we got out of the simulations.  That remaining five percent was lost to harmonic waves. But improved feedback flow control increased the efficiency to 99 percent in subsequent tests.

"There's pretty good reason to believe that when we scale up the experiment, it will behave in a similar fashion," the doctor said.

The computational research and physical research were both performed at the Academy. In many research environments, one of these two options is available, but rarely do researchers have both available. But both are available at the Academy and are literally in the same building.

"This is really one of the great benefits of working in this environment, here where we have both outstanding computational support and the lab has excellent experimental facilities," Dr. Siegel said.

"In this case we had to build the wave tank from scratch, but we have the lab infrastructure that supports that," he said. "We have the ability to do both here, that allows us to not just get more confidence in our results."

Cadet involvement is an integral part of obtaining and collecting these results for this project, which furthers cadet education and academic research. For Academy cadets majoring in aeronautical engineering, research is a requirement, and every semester has aero majors working side-by-side with professors on research and data collection. One cadet recently introduced to this is Cadet 1st Class Caitlin Miller, who joined the wave energy project last year.

"Last semester, we pretty much worked in parallel with researchers, providing experimental results to validate the computational simulations they'd done," she said.

"It was a lot cooler than I expected," she said. "I thought it was especially interesting, because renewable energy is one of the big things people are looking at, especially considering the finite supply of natural resources. The potential wave energy has to become the next big renewable energy source is a pretty cool thing to be part of."

She will further her research into wave energy this semester, as part of an independent study course.

The current three-year NSF grant runs through September, and another federal agency is providing $400,000 of follow-on funding to literally take the wave energy converter to the next level.

"What we have in place right now is a grant from the Department of Energy and they are funding us to do larger scale testing," Dr. Siegel said. "It's for an 18-month timeframe, basically looking at two testing campaigns at the Offshore Technology Research Center at Texas A&M."

The center has one of the world's largest wave tank facilities, which will allow the test of a larger wave energy converter, and eventually permit testing of three wave energy converters simultaneously.

"It allows us to take this one step further," he said. "Currently, we have a 1:300 scale experiment in our lab. The next phase is to do a 1:10 scale test."