Windmill with retractable funnel

[RandomThoughts]

I posted a thread in the lounge "windmill question" but I can't find it on google.

So started thread here.

Basically I was wondering why deep sea windmills did not have a canvas air foil to increase wind speed across blades. I was thinking this could best be used in areas where the large canvas sheets would not block scenary like out of view of land, sea based windmills. Or possibly if in non urban area.

The funnel would be cable retractable, and use a vain for yaw control.

I drew some images since my explanation may not have been clear.






High quality, drawings done with MS Paint, just a sketch :)

What do you think?

[kansasblue]

1. maybe some wind experts can comment on the increase but for me...

I'd be concerned about wind damage in a storm and additional cost.

I'd think it would be easier and more stable just to invest in the second simple clean windmill for additional power.

[RandomThoughts]

2. Canvas panels retract.

A wind speed sensor only extends canvas panels during wind speeds that make it most efficiant, they retract in storm conditions into the grey storage area.

Simple cable and rigging like on a mast of a sailing ship would suffice, and energy usage for occasional retraction would be minimal.

If you could double windspeed across rotors, you could either use smaller diamiter rotor, or fewer towers for same output.

question is, does second full rig, and the cost of turning second rotors cost more then just funneling more wind to existing single set of rotors.

Two panels are used for each side of the funnel box, to make the height of canvas consistent for easy withdraw, and extension.

[Kali]

3. why do you want to increase wind speed?

seems to me the machines are designed for whatever the "normal" speed is in a given situation. As someone who daydreams of reactivating an old windmill, I can tell you it is more a matter of consistant days of wind than speed. (well there does have to be a decent minimum for the old things, but we have a freind that just installed a wind generator for his house and it seems to run pretty easy on a slight breeze)

[RandomThoughts]

4. well

If a wind generator is geared for 15 m/s then it will run just fine in an average 15 m/s area.

But if you could effectively double wind speed, you could regear it for 30 m/s type resistance on turbine. Basically either by having rotors go faster, or by their being more resitence from pullied turbine. You could also use smaller rotors but get same output, which would be more efficiant also.

So more wind speed equals more power. As long as it is geared for what wind you expect. Also since wind is varible, you could get use in high wind at max wind speed, and in low wind at max wind speed.

Hi wind 30+ m/s rotors turn maximum speed

then in low 10 m/s wind conditions, funnel gets you back up to higher wind speed, and better production.

The added efficency would all depend on the trade off. Contraption cost vs added wind speed.

[RandomThoughts]

5. Base of Wind Stand

Would also have a wave genorator. Basically a string of floats that pull cables up and down, mounted along side of wind stand.

[RandomThoughts]

7. Note on flotable version

If the stands were flotable, some energy would be absorbed in the weebling of stand.

However, this would also form a shock absorber on all areas that obsorb wind force, so it might make for cheaper structure cost.

And wheebling since the pendilum effect would be in effect. Would only absorb power that was the frictional resistence to the contact at water line resisting the weeble.

Every push back by wind, slowing wind on turban, would be countered by wobble forward increasing it.

So weebly wablly deep sea turbans could still be as efficiant.

[kristopher]

8. Wind speed matters a great deal.

Take a look at this website and note the graph.
http://www.talentfactory.dk/en/tour/wres/enrspeed.htm

[zipplewrath]

11. Technically, total pressure mattters

Wind speed is another measure of dynamic pressure. The total pressure (and the total available energy) of the wind will be a combination of the static (atmospheric) pressure and the dynamic pressure. This device only trades a lower static pressure for a higher dynamic pressure. It's called the "venturi effect".

[kristopher]

6. Not really a new idea.

http://www.technologyreview.com/energy/21737/?a=f

The basic problem is that this type of approach can't be scaled up to megawatt sized systems. For example, the diameter of offshore rotors have a swept area with more square footage than a football field - including endzones - and they are getting larger. The towers are an expensive component of the system and you get a better return going larger than building more towers for smaller systems that have greater efficiency through the use of a a cowling. That doesn't mean there is no market for this approach. In areas where space is a constraint, it may be more profitable to use smaller turbines with cowlings.

Keep thinking though. There will be a lot of opportunities for innovation going forward.

[RandomThoughts]

9. Good link thanks.

The thing I was thinking is that you not only get the effect of keeping greater wind on turban (although square design loses some of that) You also get the forward projected increase by fat far side.

As far as size goes, you might have to add supports from front of funnel to yaw pivot point for stability, alternatively you could use a suspention cable from extension on top of tower to hold weight of funel, and counterbalance of vein.

But the important part is.

This design gives you auto yaw control solving the problem of non perpendicular wind direction.

However, it may be more efficiant to just make tower higher, but I think that even has diminisioning returns.

Do you know if any of these ideas are different?
yaw control from funnel. Retractable canvas for funnel, and a floatable design for deep sea usage?

[RandomThoughts]

15. Clarification

"But the important part is."

Important part versus part of article that in linked article design requires direct wind direction. The funnel has both direct wind direction by yaw and funneling, and it has the capture effect like the article.

Some smart person could probably make the thing circular not square. and get the same effect as the people in that article spoke about.

[zipplewrath]

10. You haven't added any energy

The purpose of this is to capture more air, and therefor more energy. Typically this is accomplished by just making bigger blades, or more of them. Air speed at the blade is relatively insignificant (over some reasonable velocity range). The increased velocity in this manner doesn't increase the total energy of the wind. You're just trading velocity (dynamic pressure) for (static) pressure. The total pressure (static + dynamic) doesn't change. Most wind mills have a maximum velocity that isn't all that much higher than its optimal velocity. They have govenor systems on them to keep them from spinning too fast in high winds.

[RandomThoughts]

12. Not sure about that.

Are you saying that added preasure caused by funneling air, would increase air preasure, but that preasure would not translate to higher force on rotors?

I would think that either faster moving air across rotors, or higher preasure air across rotors, would still increase lift.

and any increase in preassure in funnel, would have to increase speed of air leaving funnel, since air would be traveling from high to low preassure. Compact, to free air.

I think this effectivly turns a 100m diamiter rotor surface, into a 400 m diamiter rotor surface (minus some loss) since air that would never touch rotors without funnel now crosses them.

[Kali]

13. I can't make that google search work either - use the simple or advanced DU search

below the google search and search for yourself as "author"

oops, you have to be a donor. here is the link: http://www.democraticunderground.com/discuss/duboard.php?az=show_topic&forum=105&topic_id=8306674

[RandomThoughts]

14. I think the negative trade off would be canvas lifespan.

Windmills are said to last 20 years.

I am not sure of sail durability or lifespan. But it has to be at least 5 years. Simply because sailing ships would sail around from port to port many years ago for that amount of time.

I would guess with new tech, effective canvas sails could be made with as much as 10 year life span, and the simple gearing for retraction and rigging would make it low maintenance. Canvas replacement would not be complicated. So life span of contraption would go back to normal lifespan of stand alone windmill.

Contraption could be one piece set lowered on top of windmills designed to use them. And then secured at pivot point, as an alternative to individual canvas replacement.

Or better yet, raised up from bottom, so contraption could be strapped around pole lifted into place. Replacement would be just lowering contraption and replacing sails, or entire unit.

But just thinking, not sure what method would be best. But I think it would be low maintenance, since all retraction and yawing would be wind/wave/sensor driven, or remote radio, and run by simple computer program.