Hi PierreB,

Thank you very much for giving us the entire patent on Version 3 of the Active Lift Turbine.

PeterS

DaveS,

That was a nice compilation of your nonsense. It’s ridiculous for you to be dismissive of the Active Lift Turbine VAWT because it is not a good power kite. How many times do you have to be told it is not a power kite? It is not intended to be a power kite. It is a VAWT. It’s value to AWES is that it embodies a relatively new principle in a new way that might be utilized.

I have never seen evidence that Archimedes screws can exceed the Betz limit. Show me the experimental evidence. I have looked at DougS’ web site and I do not see anything that could be called a “double hub ST”. Maybe you mean his Dual Rotor ST. Whatever you are referring to, I am not aware of any of his turbines can exceed the Betz limit. DougS has never made such a claim, as far as I know. Show me the experimental evidence for your claim.

You seem to assume that any device with takes more than one “bite” of the wind can exceed the Betz limit. That is not true. So I suspect that you do not understand the Betz limit.

PeterS

DaveS,

What you are saying about “helical pitch” (your idiosyncratic and obtuse name for “blade twist”) is completely obvious. You actually think that’s an insight on your part that makes you an expert? You are laughably delusional.

When I stack Sharp Cycloturbines, each one operates at its own wind speed as determined by the wind gradient. There is no need to twist the blades.

Once VAWT are well above the ground, where the wind gradient is very gradual, the wind gradient over the height of the rotor is so small that it is not worth trying to adjust to it. If you understood VAWT, you would have known that.

HAWT rotors operate in a relatively large wind gradient. So the more advanced rotors pitch their blades, or mainly the tips of the blades, to adjust. And their blades already use blade twist to keep the desired angle of attack along the entire blade length. Then they add blade pitching to blade twist.

You main problem is that you know so little that you don’t know enough to know how little you know. And what little you do know is mostly wrong. Go fly a kite.

PeterS

DaveS,

Your nonsense mountain keeps growing higher and higher.

You are informing me that the Cyclo-Kite requires enough mass for it to fly its upwind blade pass. Do you honestly think that I don’t know that after testing hundreds of Bird Windmill blades? How dense can you be?

A “ballistic” path in physics refers to a projectile following a parabolic curve. The blade of a Cyclo-Kite does not follow a parabolic curve. Your claiming that it does is ridiculous nonsense. The blade must respond to four forces simultaneously, which are momentum, lift, gravity, and elastic cord tension. The orbit is highly distorted from a circular path. The result is very different from your assumption of  “ballistic motion”. Clearly, you do not understand “ballistic motion” nor the Cyclo-Kite.

The more you say about any subject, the worse it gets for you. The well of your physics ignorance has no bottom.

PeterS

DaveS,

You and DougS are now on record as declaring that the Active Lift Turbine is a perpetual motion machine which violates the conservation of energy law. Doug at least stated that he did not understand the concept and so suspected it was bogus. But you are confident, with no caveats.

PeterS

Hi JoeF,

“If lift is positive and drag is zero,…:

Creating lift always requires creating drag.

Kites can be described as predominantly drag based or predominantly lift based. By “lift-based” I mean that the kite produces laminar airflow over most of the upper surface when flying. By “drag-based”, I mean that the kite has acceded its stall angle and most of the airflow over the upper surface is highly turbulent.

In some few cases, controlled turbulence can be used to keep the airflow attached to the upper surface of the wing. An example is a delta-wing.

PeterS

DaveS,

“If the"active lift" VAWT cannot be fairly compared with a power kite, then why is it relevant to AWE?”

I have answered this question already a number of times. I think that your question is intended to be rhetorical, and so does not deserve an answer. But just in case you actually want to know the answer, here is the explanation once again:

Any new concept in any area of WECS might be relevant to other areas of WECS. That is why the Active Lift Turbines principles are relevant to AWE. They may be transferable or adaptable in some way so as to improve AWE.

“No one should expect to avoid engineering comparisons to power kites here.”

You are confusing the physical turbine with the principles upon which it is based. The physical turbine is not a power kite and nobody is recommending it as such. But the principles upon which it is based may or may not eventually be of benefit to power kite inventors. They will not be of benefit to you because you believe that they are part of a bogus perpetual motion machine. But others with more understanding may benefit.

“So far its just claims.”

This short article, found on their website, states that a demonstration was made. But no more details as yet.

http://www.energiesdelamer.eu/publications/72-r-d/5137-un-projet-de-turbine-a-portance-active 

I do know that they have received a lot of funding, as might be expected, and are proceeding to make prototypes.

PeterS

DaveS,

“If anyone you know of ever proposed dynamic blade twist for VAWTs, thanks for a name or link.”

I just explained to you why nobody uses twisted VAWT blades to account for a tiny wind gradient between the top and bottom of the rotor. It’s not worth it. It’s a dumb idea. You completely ignored what I said. That is rude and insulting behavior.

When VAWT become very large, then some attention will need to be given to differences in the wind speed due to the wind gradient. But reversible twist would probably be a bad idea when the pitch angle of sections of the blade could be varied instead, which would most likely be much cheaper to do.

What you want to do requires blade morphing. There are VAWT blades that change from positive to negative pitch angles by morphing, but to then try to add twist morphing as well starts to get quite complicated and probably very expensive. It’s just not worth it, at least not in the foreseeable future.

“Helical pitch” is an ambiguous term. In my experience, researchers use other terms instead. It is most often used when discussing propellers. But when applied to VAWT, like you use it, it is meaningless unless fully explained.

PeterS

DaveS,

More nonsense. You are claiming that a perpetual motion machine is not a perpetual motion machine unless it was intended to be one by the person who made it.

So now you are backing away from agreeing with DougS.

What you are now claiming is the mechanism of the Active Lift Turbine is based on a logical fallacy (meaning inconsistent with the laws of motion), and therefore cannot function as intended.

PeterS

DaveS,

If you take the time and expend the effort to be clear and complete when you say things, they will not be called “nonsense”.

PeterS

Hi PierreB,

“This reasoning doesn't look to work because when a VAWT (or all sorts of WECS comprising HAWT) moves downwind it losses a part of its power as you mentioned by describing a power kite going downwind during reel-out phase. So in a first thinking the rotor drag pressure cannot be usefully used to generate more wind power. “

Please note that that is what I said. If the whole rotor moves downwind, there is less wind speed acting on the rotor. But the Active Lift Rotor orbit does not move downwind. The blade orbit is offset to windward of the central axis of the rotor. So if the blades move downwind, they move back to revolving around the central axis is the rotor. That is what is so amazing about the way they arranged the gears. The blades do move downwind, but not relative to the central axis, only relative to the windward axis of the offset gear.

The whole rotor is offset to windward using the gear oriented by the windvane, so the rotor moves downwind, but the wind turbine as a whole does not. If you watch the animation of Version 3, you can see that the upwind blades move downwind and the downwind blades also move downwind. So both the upwind and downwind blade passes produce additional torque due to Active Lift.

I realize that the motion is highly counter-intuitive and seemingly impossible. But there it is. And the math seems to verify that. And they seem to have built a demonstration model that verified that.

PeterS

DaveS,

Nonsense. The subject was aerodynamic lift. A lifting gas rises due to buoyancy, not aerodynamic lift. Updrafts rise due to buoyancy or to deflection, not aerodynamic lift. Vertical rocket thrust is thrust, not aerodynamic lift. You are asserting that any force vector pointing upward is aerodynamic lift. According to you, if you lift your hand, that is aerodynamic lift. That is nonsense. You lose the bar bet. Clearly, you do not understand aerodynamic lift. Please go a fly a kite and stop putting nonsense on this forum. You don’t understand elementary physics. Again, you are using logic based on noticing vague similarities while missing the distinguishing differences. Again, you are trying to prove how smart you are, and again you have demonstrated the opposite.

PeterS

DaveS,

More nonsense. You are now claiming that the Cyclo-Kite is an electron!

PeterS

DaveS,

Now you are back to agreeing with DougS that the Active Lift Turbine is failed attempt to create a perpetual motion machine. Please show precisely why that is so. If you cannot, then your criticism is meaningless.

PeterS

JoeF,

You seem to be talking about the Active Lift Turbine and whether or not it could beat the Betz limit by using piezoelectric energy converters.

The blades would be mounted with pizo cells on both sides, so when both upwind and downwind, but not at the crosswind positions, pressure would be applied to the pizo cells.

The result would be additional electricity generated in addition to the normal electricity produced by the generator. However, the amount of electricity would be relatively small because pizo cells are not very efficient, as far as I know. So there would be no hope of beating the “Betz” limit for VAWT.

You are asserting that the pizo-electricity would have to come from reducing the generator electricity, because there is no “free lunch”. Please show the physical process by which that happens. In other words, please show why the pressure of each blade against its blade mounts will lower the Cp of the VAWT.

PeterS

Hi PierreB,

In answer to your questions:

-        Both the upwind and downwind blade passes of the Active Lift Turbine produce additional torque due to the blades’ aerodynamic lift vector pointing in the downwind direction.

-        Active Lift is a way of converting rotor drag (rotor pressure) into torque. By “rotor drag” (rotor pressure), I mean the rotor acting as a source of drag similar to the aerodynamic drag of a solid cylinder. For a VAWT, the rotor drag is created by the downwind pointing lift vector of the blades (both when the blades are upwind and when downwind).

I’m confident that Active Lift can increase the efficiency of a fixed-blade VAWT. I am not confident that it can raise the “Betz” limit for a VAWT.

Active Lift has been around for a long time in the form of rotor drag pulses. VAWT people know that a VAWT should not use only 2 blades. When both blades are moving across the wind, they create a very high force vector pointing in the downwind direction. That is due to the blades’ aerodynamic resultant vector which points mostly downwind. The pulses occur twice each revolution. If those pulses match a resonant frequency of the rotor/tower combination, the VAWT can shake itself to bits.

When that happens, it can be described as the energy of Active Lift acting destructively to shake the VAWT to bits. That takes a lot of energy. That force vector is not the same as the tangential thrust of the blade, which is a much smaller vector component of the blade’s aerodynamic resultant vector. So what Lecanu and his associates did was to tap that same downwind pointing force vector in a way that creates torque instead of shaking.

Hi PierreB,

Rotor pressure is created by blade lift, so they are basically the same thing.

The downwind blade pass of the Active Lift Turbine creates Active Lift, the same as for the upwind blade pass.

PeterS

Hi PierreB,

Notice that the stationary gear is offset to windward, and it is always held upwind by the tail vane. Then the other gear moved by the blade rolls around the stationary gear. When the blade is moving across the wind, either when upwind or when downwind, its normal lift applies force to turn its gear.

The blade does not store energy other than by its normal flywheel effect like other wind turbines

A subtlety is that when the blade is on the advancing side of the rotor, centrifugal force produces negative torque. But that negative torque is balanced by the centrifugal force acting on the retreating side of the rotor to produce a positive torque. So centrifugal force acting on the blade does not affect the torque.

PeterS

Hi PierreB,

Yes, that’s right. The stationary gear moves only when the tail vane orients to a new wind direction.

PeterS

DaveS,

I do consider the Active Lift Turbine to be a “breakthrough” because it a new way to increase the torque of a VAWT. The evidence for that breakthrough has been presented. And research is continuing. If you dispute it, then be specific about where there is an error. So far, you have provided nothing.

PeterS