TouchWind

[Windy_Skies]

Unlike here, the comments under the video have some insights. For example:

I am a retired aeronautical engineer that worked for 20 yrs for a manufacture of aircraft generators and Emergency ram air turbines. Have examined vertical wind turbines years ago.
Let start at the response of this wind turbine design to the variation of wind speed that have cause gear boxes and turbine blades to premature fail. The time constant of the turbine blades, gearbox, and generator are no different then horizontal wind turbines. The time constant for the tilt of the tower is at least an order of magnitude and likely two orders of magnitude slower then the rate of change that cause the turbine damage. It will not help.
The power that can be harvested from the wind is a fraction of the frontal area of the turbine. Tilting the swept disk of the wind turbine reduces that area time the sine of the axis of the turbine to wind direction. And as the turbine tilts the disk drops closer to the ocean in slower winds. So at 45 degrees both sine and cosine is 70% of the horizontal axis turbine. The lift of a tilted disk will help eliminate the need for pitch control and the drive to aim the turbine into the wind. The lift will be enhanced by ground effect, the wake stops when it hits the ocean. The wake of a turbine in a wind farm are going to interact. My guess is that they will piling up wakes, will increase the ground effect which will decrease the frontal area of wind turbines deeper in the wind farm array from the wind entering the farm.
Finally the reason for two blade choice is structural. Consider that the swept area, angle of attack, and relative wind speed changes with position. This is seen in helicopter blades. The preceding blade has a higher relative wind so even in straight flight the angle of attack is reduced. The receding blade has a lower relative wind so the angle of attack is increased. For a two bladed system with fixed relative angles of the blades dynamics is used to achieve the same angle of attack between preceding and receding blades. Gyrocopter blades do not have a fixed axis of rotation of the blades to the body of the copter. What is the relationship in this wind turbine, not stated.
Majority of helicopters have three blades and only the small and simplest helicopters choose two blades. Simply put the fluctuation of lift and thrust of the three blade together is less then two blades. Less stress on the gear box and engine.

also wonder how they plan to deal with the sideways overturning moment. because it acts like an autogyro the advancing blade makes much more lift than the retreating one without cyclic pitch control and/or significant blade flapping, trying to tip the tower over sideways. Cyclic pitch or blade flapping would dramatically reduce the working lifetime compared to conventional wind turbines, which would kind of defeat the purpose.
This design also puts the main bearing in tension with significant side loads that are always in the same direction, which makes the bearing much more expensive and dramatically reduces it’s lifetime compared to simple compression in normal wind turbines.

The inevitable encounter with the legendary ‘rogue wave’ will test this device.
Rogue waves are simply the random concurrence of all the wave and swell components at a given point, and are far more common than freakish.
And, of course, a three-bladed arrangement enjoys fundamental balance advantages, which grow exponentially as speed increases.

I wonder how reliable the bearings will be. Conventional WT has two load directions but this requires at least three some asymmetrical and they have to be able to change progressively. Now put that in sea environment and ask it to work for 20 years…I bet it can’t be done reliably

No, that’s not an uniblade. It’s an asymetric dual-blade rotor. Uniblade rotors do exist already, are used by French operator EdF in Greece, and show much higher performances.

200m rotor, on something floating in the North Atlantic, which sometimes gets 80’/24m waves
( “rogue” waves, from constructive-interference between combined waves ),
strikes me as … “optimistic”.

To me it seems that sticking the things away from rogue waves would be saner?

but that negates the whole point of the things…

ESA mapped rogue-waves, by satellite, iirc…

I wonder if there is some areas of the ocean which just have less of them, or less of the big ones?

Something like that was built in Germany in the 1980s as ‘Growian’ (Großwindanlage). The blade was shown at the Hannover fair. But somehow it failed in practical application, perhaps due to bearing problems with the asymmetric wind force. So I assume that this breakthrough will break again

“The partners and partly also the BMFT also operated the project with political motives. Günther Klätte, board member of the RWE, said at a general meeting of the company: “We need Growian (large wind turbines) to prove that it is not possible” and explained that Growian is something like an educational model to convert nuclear power opponents to true faith.”

The biggest turbine (type MySE 16-260) of the China Three Gorges Corporation has a max power rating of 16 Megawatts and are designed to operate in tropic storms that are occuring yearly in the South China Sea. The turbine remains operable at wind speeds up to 79,8 meters per second or 287 km/h. The efficiency of the turbine is nearing 90% of the Betz’s coefficient (max achievable extraction of wind power by a wind turbine, is 59.3% in accordance with Betz law).
It would be interesting to see the efficiency of the one blade turbine mentioned in the video.

Their is no way a turbines OPERATES in winds that fast, they mearly survive them. All turbines have a cutout speed where they apply brakes and stop turning. What your quoting is the wind speed which would overwhelm and utterly destroy the turbine. Fortunatly it is a speed well above even catagory 5 hurricane winds and is only a little below the highest hurricane speed ever recorded a 96 m/s so if the engineering is accurate it is a very durable turbine.

Doug comments:

Neal: The reason nearly all small wind turbine companies have gone out of business is solar prices suddenly dropped tenfold. Wind turbines of any size have to be built to last 20 years. is your car alternator going to spin for 20 years of continuous driving? No, and imagine how long it would last if you were to drive your car 24 hours a day,. Maybe your car alternator would last 6 months? And the alternator operates under controlled conditions, whereas wind storms can easily force ten times the rated power onto a wind turbine. Wind turbines can be ripped apart by sudden high gusts, shredded by hail, abraded by rain or even dust in the air, oscillated and vibrated to death in gusts or whenever any imbalance might occur . And your turbine needs a tall, very strong support structure. And cabling - buried. And disconnect switches. And a charge controller with batteries, or grid-tie inverter. And someone has to install all that, and they need to know what they are doing. Meanwhile, you can buy cheap turbines on Ebay - here’s one for $145: 1200W Wind Turbine Generator Kit 5 Blades Windmill DC 12/24V Charger Controller 241364504197 | eBay How long would it last? How much power would it make? Hard to say, but at that price, best to make sure you don’t put it into a truly strong wind. Good turbines cost a lot more, due to requiring rare earth magnets, since a car alternator would have trouble producing a charging voltage at the relatively low RPM of a wind turbine, and they need to b super-sensitive for light winds, and yet super-strong for high winds. Not easy.

If Darius VAWTs are mostly held back by bearing challenges with one blade passing through the tower shadow, surely this has that issue? …and gyro loads from adjusting for gusts and from waves! 200m blade seems unlikely to me. However, small scale deployment might be cheap enough even with ruggedised bearings if the higher winds and reduced wake claims are valid. Certainly a fresh idea anyway…

Uneven forces on the rotor bearing may be less of a problem when the mast isn’t cemented into the ground but designed to bob around on the waves - where the top of the mast can just translate sideways as a result of rythmic sideways forces. I wonder if the main problem is indeed sideways forces, because you’d still have the same problem with “sideways” rotational moments.

I think you misunderstood. The issue is that a rotating turbine is a gyroscope. Think of a normal wind turbine. If the wind changes direction, it has to yaw to face the wind (as a wind from the side wouldn’t be useful). If the turbine is rotating and yawing at the same time, the gyroscopic effect will twist the turbine either up or down depending on the direction if it has 3 (or more) blades. If it has only 2 blades, the same thing happens except the strength of the gyroscopic effect varies. It’s strongest when the blades are in vertical position and the weakest when they’re in the horizontal position. This varying gyroscopic effect rattles the tower can causes it to wear out faster than otherwise.

That’s technically a two bladed turbine, designed as a single blade, which doesn’t give any significant benefit, but a lot of disadvantages. Conventional pitch control isn’t very problematic, and has multiple significant to huge advantages over tilting the whole construction. The “uniblade” design makes the issues with making and transporting big turbines with that design as bad as conventional turbine designs with twice the rotor diameter,

Will the wind be directed downwards? Sure, typically yes, slightly at least. Will that increase net power generation compared to just utilizing the wind in the best ways we know, and/or decrease cost of the power generated? Definitely no! There’s no free lunch in physics, if you redirect the flow you’re not utilizing the energy in the wind as efficiently as you could have, and can’t “gather” and focus airflow from way above the turbines that way.

why is it almost at sea level? the winds is up not down there

The export voltage is 66kV or 132kV - for a 15MW turbine that means current is pretty low so losses at anticipated distances from shore will be manageable. Larger offshore wind parks will only be running 10’s of kilometres to an offshore substation where the voltage can be transformed even higher to efficiently transport to shore