Hydrodynamic Analysis of a Wave Energy Converter (WEC)

Presenter Information

A. Kapperman
B. Rodriguez
A. Daniels
C. Harrison
P. Tubuntoeng
L. Fernandez de Valderrama
B. Labban
J. Whipple
C. AkanFollow
N. Ozdemir

Faculty Sponsor

Dr. Cigdem Akan, Dr. Nilufer Ozdemir

Faculty Sponsor College

College of Computing, Engineering & Construction

Faculty Sponsor Department

Engineering

Location

SOARS Virtual Conference

Presentation Website

https://unfsoars.domains.unf.edu/2021/posters/hydrodynamic-analysis-of-a-wave-energy-converter-wec/

Keywords

SOARS (Conference) (2021 : University of North Florida) – Archives; SOARS (Conference) (2021 : University of North Florida) – Posters; University of North Florida -- Students -- Research – Posters; University of North Florida. Office of Undergraduate Research; University of North Florida. Graduate School; College students – Research -- Florida – Jacksonville – Posters; University of North Florida – Undergraduates -- Research – Posters; University of North Florida. School of Engineering -- Research – Posters; Civil engineering -- Research – Posters; Honorable Mention Award Winner

Abstract

Honorable Mention Winner

The UNF CREW competing in the U.S. Department of Energy 2021 Marine Energy Collegiate Competition developed a Wave Energy Converter (WEC) for quick deployment in disaster relief areas. When natural disasters disable coastal power grids, a WEC can be easily deployed close to shore and serve as a source of electricity. The ocean waves move magnets through a coil wired within the WEC to generate electricity. To initiate the design process, ANSYS AQWA software simulated both the oceanic environment and the device’s response in the WEC’s testing conditions. AQWA allows the user to change device dimensions easily and optimize the design ahead of physical construction. The resulting WEC proof of concept minimized prototype manufacturing waste and cost by eliminating poor designs in advance. The simulated geometry neglected hollow sections and used unidirectional, regular waves to account for software limitations. The software simulated the WEC for 20 seconds in an oceanic environment with a 40-meter depth and a 0.25-meter amplitude regular wave. Simulations produced graphs and animations describing the forces acting on the WEC as well as the WEC’s movement. The animation proved that the WEC reacts well in similar physical testing conditions. Based on the simulation results, the team constructed a 3D model for small-scale testing. Future investigations will involve more complex designs. Research conducted onward will focus on mass-damper systems and contact surfaces provided in the software.

Comments

Audio Presentation Transcript:

“This presentation is brought to you by the UNF CREW. CREW stands for Cheap Renewable Energy from Waves. The UNF CREW is competing in the U.S. Department of Energy’s 2021 Marine Energy Collegiate Competition. The CREW’s mission is to provide renewable energy to coastal areas that need it. That mission drives the team’s primary objective: to develop a Wave Energy Converter (WEC). While the CREW initiative involves many projects including those focusing on engineering and business, the presentation you are about to see focuses on an engineering simulation meant to aid in product design.”

Presentation Beginning
[Brianna Rodriguez]
Hi, I am Brianna Rodriguez.

[Andy Kapperman]
And I am Andy Kapperman.

[Brianna Rodriguez]
And we are two members of the UNF CREW presenting our research on hydrodynamic analysis of wave energy converters, or also known as WECs. So, currently, the team is looking to advance the marine energy field. We want to create WECs to deploy in disaster relief areas. Coastal areas often get hit by natural disasters like hurricanes or tsunamis and they leave their power grid defenseless. These nice, handy-dandy wave energy converters can provide temporary relief to those situations. Currently there is a lack of research in this field. There’s minimal foundation, but there’s really not much to work with. And we’re trying to pave a new way and research these wave energy converters to help create more for future endeavors.

Specifically, the type of device we want to make is a point absorber. It’s a small, easily deployable WEC and inside of it, it houses magnets and coils of wire. So, what happens is, this nice WEC floats up and down on the ocean surface and the motion of the waves allows the coils to go up and down, passing through these magnets. And that motion allows electricity to generate. And you can see this point absorber in figure one, it has the float on top and in the shaft there’s coils and magnets housed.

[Andy Kapperman]
Now that we’ve talked a bit about the background of what a WEC point absorber is, let’s discuss the design process of actually making one. To kick off the designing, what we wanted to do is be able to simulate the WEC and how it would act when actually put out into a real environment and simulation would provide us information about its movement in the ocean, how waves were interacting with it, and give us specific numbers about forces that were being applied to it, like buoyant forces. Now, how are we going to do that? We were able to simulate the movement of the WEC using the AQWA ANSYS software package. Now, what that allowed us to do is throw a certain geometry out into a marine environment, throw some waves at it, and see what happens.
Why bother with this? In addition to helping with the design process and everything, it had some major advantages, such as minimizing waste and cost during the prototyping process, because if we can make mistakes while simulating a device digitally, we don’t have to make them physically. So that, you know, keeps the costs down as far as physical materials go. And it just allows us to better understand – more quickly – what works and what doesn’t.
When doing the simulation, we had to make a couple of simplifications in order to help the software package be able to produce valid results that would be meaningful to us. One such simplification was hollowed shafts and different floats. We were able to neglect those and model them just as simple, solid shapes. We also took some of the mass properties and rounded them to make the computations a bit easier and speed up simulation times. And we applied unidirectional waves – which are just waves moving in one direction – and uniform regular waves. So waves with very normal, cyclic patterns. And that kept the simulation results fairly reasonable. And the reason we were able to do that was even though we made some simplifications to the simulation itself, the results were still valid enough to reflect what would actually happen when the WEC would be thrown into an actual environment. We didn’t lose any accuracy that was significant enough to be majorly impactful on the output.

[Brianna Rodriguez]
So based on these simplifications, we are allowed to take our next step forward in our journey and actually begin to create a model of a WEC. So what we did was we modeled a cylindrical wave energy converter and this allowed me and Andy to become familiar with AQWA and learn how to generate these graphs and these animations to really give us a good grasp of how this energy converter is going to act and the oceanic environment. So some of the dimensions we use for this cylindrical WEC was a 1-meter diameter and a 2-meter length. And so how that came out looking was this nice cylindrical shape right here as seen in figure 2. And when you look at this, you’re wondering, like, why is half of it green? Why is half of it Brown? And this is because of one of the requirements of the software. That nice demarcation line in the middle between the two colors, shows where a water line acts on our wave energy converter, and that’s how we calculate its position and all these other great results that Andy will be discussing in the data section.
So, before we actually get into our data, we need to discuss our ideal testing conditions and these are included in our Parameters [section]. So some of the parameters we use for our simulation included a water depth of 40 meters, a nice wave amplitude of about 0.25 meters, and a cable stiffness of 30 Newtons per meters. And you may be curious where this cable is coming from. And if we kind of look back at figure 1, we see that our point absorber is tethered to the ocean floor. We need something to keep it grounded to the ocean floor so that it’s just not free floating in the ocean. So that cable stiffness references like how tight that cable is keeping it tethered to the ocean bed. And we also have a nice wave speed of about 0.1 meters per second. Nothing too fast. Nothing too crazy. And this whole simulation goes on for about 20 seconds.

[Andy Kapperman]
With a lot of the simulation parameters that Bri was talking about, we’re now able to discuss the actual results that the simulation produced. The simulation produced a number of things: diagrams relating motion to time or forces to time. And up here we can see a pressure diagram which illustrates the different pressures that were acting on the WEC above and below the water. And that’s important because as Bri was talking about before, there’s that line that slices the WEC in half at the waterline. So on this diagram, we can see different colors above and below that line. And those different colors reflect the different pressures that are being exerted on the WEC, depending on the water that’s pushing in and around it and the different movement of the wave as the WEC moves up and down. So that’s a bit about the pressure contour diagram that we’re looking at there. The simulation also produced an animation that helps us understand exactly how the WEC is interacting with the different waves. And there’s a screenshot down here kind of giving you a look at what the animation looks like and a QR code just below it, that if you scan it, will take you directly to a video showing the animation. Now, what the animation shows is about a 22 second video. It’ll show how the wave moves the WEC device up and down and how it bobs from side to side. So we can get an idea of how the mooring cables, whether or not it anchors the WEC enough to hold it in place. We can get an idea of if the wave is causing it to drift too far from one side to the other. We just, we get a general picture of how the device is actually responding in a simulated environment.
So all that happened in the simulation stage. What does that get us? Well, the simulation proved very successful. It gave us the green light to move forward to the next stage of design, which would actually be that prototyping that we were saving money from before. And we were able to see that the simulation was successful. So let’s go ahead and actually make a physical device. So that’s what we did. And the QR code over here, right next to “2D to 3D” [heading]. If you scan that, it’ll take you to a link showing us testing the actual 3D model that we constructed. And we were able to create a model of the WEC, put it into a wave tank, apply regular waves to it, and watch it bob up and down and generate electricity. And whenever that worked, that was really an exciting moment. When we saw the WEC device that we’d been simulating, designing, we saw actually generate electricity.

[Brianna Rodriguez]
Based on this past success, looking onwards, we want to pursue more complex designs that involve translational shaft motion, on the WEC. So to specifically accomplish this goal, we are going to investigate two areas and one of them is going to be a mass damper system and also AQWA contact surfaces. And that kind of includes fenders. And what these do is they allow relative motion to occur between two surfaces. So if we look at these figures right here, this illustrates the complex intermediate WEC design we do want to simulate in the future. And what will be occurring is that the float and the shaft are one piece, and this base will be moving up and down and that will allow the electricity to generate. So we are going to be directing most of our efforts into figuring out how to simulate that motion to see if this will succeed in the oceanic environment. That concludes our presentation. I’m Brianna, and I’m Andy, and thanks for joining us.

Slide with Text

>>Thank You<<

Presentation Conclusion

Streaming Media 1

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