Hi DougS,

Thanks for taking the time to list your general objections to VAWT. I agree with some of them and not others, but that is neither here nor there. You did not show why the Active Lift Turbine is a perpetual motion machine. But if you ever find a way to demonstrate that it is, I would like to see it.

I accept that you believe that the Active Lift Turbine does not work, has no value, and is just another crackpot idea.

PeterS

DougS,

Thank you very much for your comments. I am most interested in your observation of a momentary, initial burst of power when you do truck testing. I want to know more about it. It may apply to all wind turbines and kites, and there might be some way to make use of it.

The only thing I can think of that is at all similar is how a too narrow wind tunnel (blockage) can increase the power of a wind turbine model significantly and give a false Cp for that model.

Here is an hypothesis based on that analogy and on my very insufficient knowledge of what you observed: Let’s assume that the total airflow of the truck and the wind turbine, when the turbine is released to start spinning, is different from after the turbine has spun for a while. That seems clear.

So maybe the airflow from the truck creates the equivalent of a wind tunnel blockage when the wind turbine is stopped and also while initially accelerating.

But then, when the wind turbine is at full speed (the design TSR), the spreading of the air in front of the turbine (the bubble) pushes away the airflow created by the truck that created the initial blockage.

That hypothesis seems consistent with the facts as I understand them, at least so far. I am visualizing two vortexes created by the front of the truck that move upward and rearward so as to approach the sides of the turbine. So the vortexes act like the walls of a too narrow wind tunnel and force higher velocity air through the rotor disc area. But once the rotor accelerates, it creates a back pressure in front of it which blows the two vortexes farther away from the rotor disc. There would be a short lag time for that to happen. During that lag time, while the rotor was accelerating, more air than normal would be forced through the rotor disc, thus producing a momentary burst of power above normal.

Does this make any sense to you in terms of a possible explanation?

I just remembered something else that might be relevant to that hypothesis. Many decades ago, and experiment was done to increase HAWT efficiency. A large delta shape was mounted on a tower, with the point facing into the wind. The delta shape was given a high angle of attack. So it acted like a delta-wing aircraft, like the Concord. Delta wings can create high lift because they create large vortexes that spin over each side of the wing as they move rearward. In this case, two, small HAWT were placed toward the rear of the delta-wing where they were impacted by the very rapidly spinning vortexes. As a result, the HAWT spun very fast with a lot of power. I think that they rotated opposite the direction of spin of the vortexes so as to maximize the apparent wind speed on the blades. The concept was also suggested for use in water currents since it could accelerate and concentrate the flow of water through the HAWT. As I recall, the design worked, but it was not necessarily practical due to the large size of the delta-wing, and perhaps to the difficulty of protecting the whole device in high winds.

The truck may be acting somewhat like a delta-wing to create vortexes. That fits with what I said above.

But another possibility is that one of those vortexes might impact the rotor disc area directly to increase lift. Then, as the turbine creates some back pressure and diverts wind from in front of it, it may blow that vortex to the side a bit so that it no longer adds a bust of energy. This doesn’t sound very likely to me. The first hypothesis seems more likely.

As for improving on the Darrieus machines, the Sharp Cycloturbine already does that, and without any additional cost. But I can’t get researchers to take it seriously because it looks too simple, and because it can’t be analyzed mathematically, or simulated, as yet. I should be building models instead of Emailing.

PeterS

DaveS,

You keep repeating nonsense. Nobody has ever claimed that a wind gradient has no effect. The issue is the kind of effect and relative to what. My comments to JoeF, coming up, my help to clarify what I mean.

PeterS

DaveS,

I have no idea what you are referring to. Please include what you are responding to when you post.

PeterS

DaveS,

It is not clear to whom or about what you are responding. Please include what you are referring to and who you are addressing.

PeterS

Hi Pierre,

I agree with your comments.

PeterS

Hi PierreB,

Yes, I agree.

PeterS

Hi Joe,

Thanks for working on clarifications. No, the labels you are using are incorrect. Here’s why:

“advancing” means advancing toward the true wind.

“retreating” means retreating away from the true wind.

“upwind” means the side closest to the true wind, also known as the windward half of the orbit.

“downwind” means the side farthest from the true wind, also known as the leeward half of the orbit.

Something to keep in mind is that the circular orbit become highly distorted due to using elastic cords to suspend the blade. The elastic cords store and release energy to assist the blade. Also, the anchor points oscillate in the upwind/downwind plane, but that is a relatively small distance as compared to the orbit radius, so it can be ignored when describing the orbit.

Here are some of the changes to the orbit that occur:

The upwind blade pass is flattened (shortened radius) because Active Lift pushes the blade downwind.

The downwind blade pass is elongated (lengthened radius) because Active Lift pushes the blade downwind, and because the centrifugal potential energy stored during the upwind blade pass is released during the downwind blade pass.

So due to Active Lift, the blade orbit is eccentric and shifted in the downwind direction.

The bottom, advancing side of the orbit is much larger in radius than the top, retreating side of the orbit. That is due to gravity acting on the blade to contract or stretch the elastic blade cords. You can observe that in videos. The blade flies much farther below its anchor points than above its anchor points.

          Consequently, the blade begins its upward, upwind blade pass with a lot of stretch and extra tension (stored energy) in the elastic cords. As the blade climbs, the cords contract. That helps the blade to rise all the way up and over the top of the orbit. It is a bit like an ice skater pulling in her arms while doing a spin. It makes her spin faster.

          Something else to know that can simplify is this: When the blade orbit of cycloturbines are described, the quadrants are numbered “1”, “2”, “3”, and “4”. That gets rid of a lot of words and becomes easier to understand once the quadrants are memorized. The numbering is counter-clockwise. Quadrant number 1 begins with the blade heading directly into the wind. That position is also called the “zero azimuth angle”. For the Bird Windmill blade/kite, quadrant number 1 is on the bottom and upwind, where the blade is beginning to climb.

          However, since a drawing can show the orbit revolving either counter-clockwise or clockwise (seeing the same orbit from opposite sides), using the numbers helps keep things clear. So I recommend it.

PeterS

Hi Joe,

Ooops! Sorry I hit “reply all” instead of “reply”. Habit.

But since everyone has that information to work with, I’ll send this Email to “reply all” too, so as to help clarify. I think that the information is useful.

I found a video which shows some of the distortion of the blade orbit.

https://www.youtube.com/watch?v=UKvRsBgeLQc  

At the beginning of the video, it can be seen that the bottom half of the orbit has a radius that is much larger than the radius of the upper half of the orbit. This difference is larger when the orbit diameter is larger (for a given wind speed).

When the orbit radius is small, not much distortion can be seen. It’s there, but not pronounced, because the elastic cords are under high tension. Here is an example:

https://www.youtube.com/watch?v=cxEdUlbqwsg  

Peter

Hi Joe,

Yes, that is the standard for naming cycloturbine quadrants. Thanks for helping with the clarification.

PeterS