Show notes
Allen sat down with Nicholas Gaudern, CTO of PowerCurve, at ACP in Minneapolis to discuss the importance of aerodynamic blade optimizations and upgrades during wind turbine repowering. PowerCurve's AeroVista tool can help operators address leading-edge erosion and suboptimal blade designs to mitigate aerodynamic losses.
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Allen Hall: Welcome to the special edition of the Uptime Wind Energy Podcast. I'm your host, Allen Hall, and I am at ACP 2024 in Minneapolis with Nicholas Gaudern the CTO of PowerCurve. And PowerCurve is based in Denmark, and they are aerodynamic blade experts. And Nicolas background is with Vestas, and now he's a freelancer, so to speak, at PowerCurve.
And PowerCurve is where WeatherGuard goes for aerodynamic help. Yes, and a lot of other operators around the world reach out to power curve. So we thought it'd be a good time to talk to Nicholas because of all the repower activity in the United States and aerodynamic upgrades that should be happening on the ground.
Nicholas Gaudern: Yes. Yeah.
Allen Hall: That, that the opportunities being passed by, which is a total mistake, absolutely total mistake. And Nicholas, welcome to the program. And I want to walk through that.
Nicholas Gaudern: Thanks for having me back Allen. It's really nice to talk to you again and and another show. So always good.
Allen Hall: So in Texas, Oklahoma, Kansas, all over the United States, the IRA bill is kicking in and there's a lot of repowering happening at the moment.
And when I talk to operators about lightning protection, they're like, yeah, absolutely. We need to put additional lightning protection on because we know from the previous blades that they were not great. And we've heard rumors that these blades are not great. Our new blades are not great. So for lightning protection, that's pretty easy, but they also don't they don't think about the aerodynamic aspects.
Nicholas Gaudern: No not necessarily. And I think it's it risks being a really big missed opportunity. Yes. Because whenever you've got a blade on the ground, that is obviously an easier time to be doing any upgrade work, repair work, enhancement, whatever you want to do. So when you've got a blade on the ground, you should absolutely be considering the optimization potential, the aerodynamic optimization potential.
So when you're repowering, you may think that you have the latest and greatest blade. It's very unlikely that you do. The blade may have been designed many years ago. And even if it is more recent, we haven't come across a single blade that we can optimize, not a single one. And that's not because the OEMs are doing a bad job.
It's just that they have a lot of different constraints. That can be time pressure, it can be cost, it can be materials, whatever. It maybe means they haven't spent as much time as they could have done on squeezing every last bit of aerodynamic performance out. Which is fine. Maybe, the business case for them doesn't support that.
But for the operator, it absolutely does. Because if you can get another half percent, one percent, two percent AEP over the lifetime of that product, That's a hugely powerful lever to pull.
Allen Hall: Because the blades, let's just choose a 2X machine. Sure. Which there's a lot of 2X machines going in the United States at the moment.
Those 2X blades were designed pre pandemic. Yep. Most likely. And they were designed pre 3D aerodynamic analysis. They were designed with the BEM method.
Nicholas Gaudern: Yeah even today using a fully 3D approach is very rare. Yeah. And there are some good reasons for that. Obviously, it is computationally expensive.
But if you really want to optimize a blade, particularly down towards the root, you have to do a CFD based approach. Because that's very 3D flow down there. And this BEM method, the blade element momentum method it's been used to design every blade out there. I'm pretty confident in saying that.
I'm sure it's going to be designing many blades many years to come. Sure. Because it's good, it's computationally quick, But it's not going to give you the best possible blade, particularly when it comes to optimizing that root region or the tip region where the flow is much more three dimensional.
Allen Hall: So I seen VGs on new blades down close to the hub. That's an option. It appears to be an option for some operators and they'll do the ones near the hub because the arrow efficiency there is so poor that's obvious.
Nicholas Gaudern: It is, yeah. The aerofoil is down towards the the hub. They're basically cylinders, they're not the kind of thing you would expect to see on a flying device. So they are playing a structural role. They have to be that thick to get enough material into the blade so it's stiff enough to withstand the loads. So it's a structurally constrained area of the blade. But that doesn't mean you shouldn't pay attention to the aerodynamics.
Allen Hall: At the tip, you don't see many VGs being added. That's it. On the ground or even on new blades just being offered. It seems like what happens is the OEMs come back a year or two later, then offer, Hey, we got this aerodynamic upgrade. At that point, it's like too late because the business case is over.
As soon as you got to get someone on a lift or someone on ropes. It's just, it's hard.
Nicholas Gaudern: You need to get more AEP, of course, to pay for it. So you really should think about vortex generators in kind of two, two families, you've got root region vortex generators, you've got tip region vortex generators. And the ones towards the root, I would say, there's no reason that every blade shouldn't have them.
They're a no brainer. And the reason I say that is because of these thick aerofoils. The thick aerofoils aren't going to perform particularly well. There's going to be stalled, three dimensional flow in the root, and vortex generators can help mitigate some of that. So you're going to get some AP back, but of course, because it's near the root of the blade, there's not such a long moment arm.
Even if you get loads more lift there, you can't just magic more torque, but you should put them there because it's an easy thing to do and you'll get some more energy. Of course, they have to be in the right place, we can help with that. Out towards the tip, it's a little bit of a different problem.
So out towards the tip, if a blade designer has done a good job in principle on a brand new perfectly manufactured blade, a VG near the tip isn't going to add much energy Because the blade can actually generate all the lift it wants without any problem, the flow is fairly two dimensional, it's all good.
But I, you'll notice I use the word perfectly designed, perfectly manufactured, perfect surface condition. Of course we know when we go out in the field that is not the case. Even manufactured blades have some variation in the leading edge shapes. They're handcrafted products. As soon as they're exposed to the atmosphere, that surface starts to get a little bit rougher, maybe gets eroded.
And at that point, that's when the blade is actually going to lose AEP because that leading edge damage of contamination, a ruffling of the surface, all those kind of things, they lose your lift and the increase your drag. So vortex generators towards the tip, they really come into their own when you have this kind of suboptimal blade surface.
Yeah. So that's why you have to treat them as two, two families. One is boosting the fundamental performance of the blade and the root. The other is recovering losses towards the tip.
Allen Hall: And if you're an operator in Oklahoma, Texas, Kansas, anywhere, there is a plow field, right? Where there's farmers and activity, dirt and the dust in the air is doing a Tremendous amount of damage to the leading edges.
Yeah. So if you've had turbines out there for two, three years, you know that damage exists and your repower on the farm next door, you should be thinking about putting vortex generators on because of the leading edge erosion effect to keep the power at a high output.
Nicholas Gaudern: It's a tool for power curve robustness.
Yes. Power curves fluctuate throughout the year and you're not going to change that different densities, atmospheric conditions, things move around, but VGs are just going to push that average up. Because they're going to stop you getting into these bad situations where the flow is starting to separate, you're starting to lose lift, get that increased drag.
If you have a perfect blade with a perfect surface condition, okay, fine. Fine. Maybe focus on the root region only, but I'm yet to see many blades that are perfect.
Allen Hall: No, we've seen, Joel and I have traveled around a lot of the Midwest and usually within one year, the leading edge erosion is severe enough that it's impacting, things.
the AEP performance of that turbine. Yes. Easily.
Nicholas Gaudern: Yeah. And something that I think is probably nice to move on to now is to talk about what, how do you understand what the AEP loss is?
Allen Hall: And that's the problem. I think engineers, the operators are mostly structural people because they're trying to fix blades or gearboxes or whatever.