Wind Turbine Blades

You have some conceptual sketches to share?

The incident angle depends on wind AND rotating speed which is radius proportional. If you do not twist the blade the angle will change along the blade and reduce the efficiency due to drag increase.

The problem is generated by the relative speed of wind with respect to blade. If foil speed increases it is as the wind would act with an angle so that its force brakes the movement. This is the reason I wrote that drag increases. I know it is difficult to understand since we think in an absolute way and the effect is based on the relative movement. I shall try to find a way to explain it better. In fact the regions at low R bring also low power the best is depending on the ratio Rmax to Rmin to optimise toward the bigger radii.

If the foil considers all effects the load is mostly a bending (again depending on several factors) if not there is a torsion which adds and its effect can be important.

One of the reasons of twisted blade is the difference in surface velocities of the blade (= rω) from root to tip where as the wind is a constant velocity.

So at any wind speed, the blade at the tip will be at a velocity larger than the wind and hence will experience a drag.

What you describe has been done with vertical axis wind turbines. On a horizontal axis though I don't see how it could work.

Vertical Axis Wind Turbine was designed to respond to the ever increasing demand for wind turbines that work well in the urban environment, where wind speeds are lower and wind directions change frequently.

vertical axis wind turbines

Solar Power Generators

Vertical axis turbines have a VERY big draw back:

-As wind is perpendicular to their axis during a rotation the blades are productive for a small angle and either have a nil efficiency or even work as brakes for a big angle.

The best,with fixed blades, is to obtain an efficient effect over about 90 to 120°.

Even a cover avoids not all brake effects so that from the produced power a not neglectable part is used to compensate frictions and braking effects.

It can be corrected but it requires a very complex blade orientation system which is also sensitive to wear and has a high production and maintenance cost. Such systems are used in hydropropellers but there the cost is less important.

It is question of perception of situation. One of problems of Windpower stations is speed regulation, so to have braking effect is not bad in strong wind. But if system is optimized for weaker wind them braking should be avoided, and if this is achieved, then we are back to old problem of speed regulation. With 90 degrees exposed to wind, it would be 50% efficiency, which is at once double compared to best contemporary HWTs, and if we get 120 degrees we have 66.66% efficiency. Now just speed control is necessary. I have design that has constant efficiency of at least 95% because it is not simple >>brutta forca<< >>push my plate<< system. Anyhow, the braking could be transformed into flying againest wind, and then you have additionall force to rotate VWT in same direction, and if this blade that is also wing is moveable, it would present its surface to use >>sail Effect<< mainly, and with high speed centripetal force would spread wingblades radially out of center and use braking effect to regulate rotation speed, specially if wingblade is suspended asymetrically and wing half that is opposite to axe of suspension is heavier then other half.......

Congratulations you develop a new physic!

Even theoretically a 95% efficiency is NOT possible but if you claim it I do not doubt I am only impressed by the power of your thoughts.

May be you could explain how you define efficiency?

For your personal information even if you use the lever effect of an eccentric axis with respect to the center of the aerodynamic force you cannot compensate the effect of the angle.

But it is better to have a dream and fight for it.

If you need support I am willing to give it to you, not by investing money because I do not have and also do not believe in what you claim as long as I do not have a proof even on paper and not only qualitatively but by analyse of the principles and establish quantitavely if you may be right.

Present type of horizontal wind turbines evolved that way as best solution there is. So if it is horizontal rotation axe, forget it!

VWT is entirely something else. There has been several threads on wind turbines already, so why start another one?

I had similar ideas with springs instead of motors that would turn blades according to strength of wind, but then I realized there is better and more efficient way to use wind.....

I also have idea how to get such uniform width turbine wings like You describe that would be extremely cheap, but they would be used only for small scale generators, even if it would be possible to produce various length of wings according to need.

I am in process of patent application so I cannot reveal details as yet, but I would do it soon enough.

Regards from Zagreb, the capitol of Croatia, Europe!

"Present type of horizontal wind turbines evolved that way as best solution there is."

Please explain why you think this. why only 3 blades is best, especially in the center area of

the rotor? If you are referring to blade profile and AOA.. maybe I can see your point, but I suggest staying off of absolute statements.. It is just the best so far.

Chris

I'm not an expert with this stuff, just an enthusiast.

Angle of attack is dependent on many driving variables, such as optimum generator load speed, wind speed, rotor diameter, and the blade profile.

Personally, I'm fan of the static bulb center, because if you were to test wind turbines in water, you will find, I think, that such low forces are generated in the center of the HA turbine, as to be negligible, and therefore wasteful. I think it better to divert that air to the tip areas of the blades, where it can get maximum leverage.

I am also inclined to try and create a system where a given turbine can find its own optimum angle of attack, by perhaps using a flexible (rubber?) blade profile, so that increased pressures will force the blade to conform to an AoA proportional to the wind pressure on it.

I am also a fan of the shape of profile developed by NASA, and the bottlenose dolphin, for best streamlined flow, and keeping that flow laminar. I think the blades should have a longer tail, but again, flexible, to decrease the turbulence. I think also that the whale tail design helps stabilize this flow... These sorts of suggestions are all in keeping with the notion of keeping with natural principles and examples, as exemplified by people like R. Buckminster Fuller.

That way, we don't have to bash our heads so much to find out what might be optimal, in reality. there are so many examples, from fish to birds and bats to maple keys. It might be helpful to create a comprehensive analysis of natural applications dealing with fluid flow.

Chris.

Hi, Chrisq288

It is not random selection but result of computer simulations. One reason why there is no more blades is weight/mass/inertia. Today's behemoths cannot even start by themselves, so they spend electricity to start. Since their blades also have to be turned by motors to change attack angle of blade, more blades would mean more weight, then whole construction would have to be more robust to take more beating from laminated wind speed and so on. I would say IMHO it is because of laminar flow of wind that beat blade in topmost position that two other blades act as counterweight that dampen that blows and resulting vibrations. I fully agree that they are inefficient and I know one design that would be much more effective, but problems start when wind become too strong. Ideally, blades should start braking as wind tops optimal usage speed. That unfortunately set too much stress on blades and whole supporting construction because of >>Sail Effect<<. I believe there is one design of blades that could stand and work in strongest wind, but I need good CFD and CAE software to test this hipotesis. Since this cannot be patented as it is children's toy in my country, I shall explain it once I would be sure that my conclusions are confirmed by computer simulations. However, I am still looking for investor that would support me at least that much that I can get CFD simulation program. But, as a toy it works perfectly :-))

Otherwise, I have plan for very cheap wind turbine, so cheap that it would not matter if wings are broken by too strong wind as they could be replaced easyly. I however believe that it would withstand great force of wind without breaking.........

Such turbine would then be easy Do It Yourself project, as main cost would be generator and main problem how to store surplus electricity/energy :-))

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Regards,

Marijan Pollak

Today's behemoths cannot even start by themselves, so they spend electricity to start.

That problem has been around for a long time.

Back in the late 1930's early 40's beforer WWII, before REP (Rural Electrical program)

Our farm (before my time) did not have electricity, My Gandpa bought a Sears and Roebuck 32 volt wind generator. This worked both ways, as it was turning it generated current, on calmer days, you turned a switch pressed a button and it drew the 32 volts from the battery to start it turning, after which, you switch it back, and it started generating.

I guess it was a behemoth for its time though.

http://www.automation.com/content/hydraulic-pitch-drives-for-wind-energy-turbines

we can never have enofh threads about wind turbines! when are we going to see hendricks design?

mine is almost ready you can see some pics of the idea at facebook here

http://www.facebook.com/home.php?#/group.php?gid=60681888393

i know every one is afraid to show thier design we have just tried to put it out there withour name and do press release and poorman copywrite with the plans, so this is an official press release of the design,for windpower inc. of miami florida all ideas property thereof.

since much of the design is "patten pending" for howlong who knows, i just looked and noticed we have the pics down, due to getting the notary stamp on the plans this week but they will be up by wed

couldn't find any pictures... please indicate when they will be available

http://thewindpowercorp.com/index.htm

here is our web site we can only put pics here because this is the only place they are copyrighted but if you go to the product page you can see some 3 d models of our concept, wich is prety simple realy, just a modified lenz2 doubled to make more power. the web site is being worked on as we speak so look for updates of the construction we did this weekend and soon to see the finished prototype

thank you..

question.. does each 'blade' rotate? or just the whole arrangment, on a single rotor?

( I realize you also show a double rotor system there)

Chris

each set of 3 blades rotate then connect to the generator in the middle by pully/belt

Oh, my....

That is unnecesary complication and totally preclude posibility of speed regulation.

I assume You write about Aurora system, dont You?

You must also then have problems with rotation direction at start?

It say "Page canot be found due to site maintenance" only....

Since I was webmaster I know that mean You did not put anything there :-((

Henrik your a total tool, that is a link to a face-book group, I think the only web-mastering you have done is in your spiderman underoos. Obviously something was posted and then removed for legal reasons, as I wrote in the original post, as is written in the group post at that fully functioning link.

If the link does not work for you maybe you should test your Commodore 64 and not accuse others of lying!

p.s we have many good investors, how are your attempts to raise capital by alienating everyone going?

Constant Chord? Not such a good idea. You probably know all about angular velocity? Good design of a wing will always require a constant lift along the total wing span. Also I will stay away from mechanical governors as they cause too much mechanical load working against pre loaded springs. do it hidraulically, maybe as a function of remote wind speed sensing? My 5 cents worth... Wangito.

By have a constant chord length, Have you considered the stress that would put on the blades, as one moves from the center to the outermost edges.

As well as the turbulence working against it

Are you concerned about the environment and about the quality of life for successive generations? Concerned also with the rising costs of traditional forms of energy? Well, a wind turbine might be just the thing for your home or business!

There are two types of wind turbines; The HAWT, or horizontal axis wind turbine, and the VAWT, the vertical axis wind turbine.The difference lies in how the rotor is attached to the apparatus – either vertically or horizontally.