Electricity Generation Using Principle of Dynamic Soaring

[activesoarer]

Hi,

Sorry this thread may not relate to slope soaring. I have a discussion with my friend on the possibility of generating electricity more efficiently by using the principle of dynamic soaring. It is difficult to explain my idea but I hope you can understand what I have drawn up.
The idea is this: we construct a wheel on the back side of the hill. Blades are attached to the wheel, the blades on the downwind turn, as in a DS circle, will be opened fully while the blades on the deadair zone will be collapsed. Will the wheel turn faster as faster similar to a DS run?
I would like to seek your opinion. Any engineer here can do an analysis on the efficiency of this DS generator as compared to conventional windmill type of generator? I think we can pack a column of these generators on the back side of the hill to generate more electricity.

Stanley Chan
Hong Kong

[shoe]

welp, there goes all the prime DS spots, taken over by the gov't for generators.... ;)

[Reed]

I'd thought about this as well. Don't know anything about engineering but personally, I'd gladly give up all the DS spots if it would allow for cheap, renewable energy.

signed,
commie-pinko-peacenik-treehugger

[bjaffee]

Wouldn't it be easier just to build a windmill?

[Brian Courtice]

I guess the hope for a this system is that you could generate more energy with a given wind velocity than would be possible with a conventional windmill.

One obvious drawback to the system is that it will only work when the winds are just right. Modern windmills are able to rotate into the wind and therefore able to take advantage of changing wind direction.

I'm not convinced a DS wind power generating system is viable, but I hope someone will prove the concept one way or another.

Very interesting!

[greg morrison]

I've also had this thought as well. You could manufacture your own "wind break" though anyplace you had sufficient wind. A slope isn't really necessary. I've read that the tip of a conventional windmill blade can spin as fast as 150 mph. I wonder how fast a "DS Windmill" would turn? I've made a few sketches (for my own amusement mainly) myself but with a slightly different approach than yours.

Greg

[bjaffee]

I understand the principle of it, it's just that a conventional windmill has all of it's blades exposed to the wind all the time...just seems more efficient.

As far as the DS windmill goes, I think you could dispense with the need for folding/feathering the bottom swinging blades by going with a counter weighted one-blade design. There are actually conventional one-bladed wind turbines...kinda strange looking but I guess they are more effecient because there are less tip-losses (there being only one tip).

[RCheroske]

I think it would work however I also think that you would get better efficiency from a prop or eggbeater type of wind generator of the same size. The reason being is that your design as shown only uses 50% - 60% of the wheel to generate power as opposed to 100% of a prop and 80%-90% of an eggbeater wind generator.

However don't let me stop you. If you think it will work then build it and try it out and prove me wrong.

[shoe]

why not just build the thing in a box with the bottom half shielded from the wind? no need for a hill at all.....

[bjaffee]

Originally posted by shoe
why not just build the thing in a box with the bottom half shielded from the wind? no need for a hill at all.....

Hah! Good point!

[Daemon]

Hmm.. how to explain this..

A conventional windmill is going to be way more efficient than this shear layer paddle wheel. An single point on a shear layer paddlewheel will never move faster than the wind. It won't remind you of DSing in any way and really isn't using the same principles.

Every efficient windmill does spin its blades faster than the wind's speed, because the blades are airfoils and generate lift, lift generates blade airspeed, blade airspeed generates apparent wind, which actually generates more lift as you rotate the blades to take advantage of the increased airspeed, and so on. It's the same reason a sailing catamaran can sail at twice the speed of the wind on a broad reach with the sail pulled in further and further as it accellerates, and an iceboat 3 or 4 times the speed of the wind (I've done 80mph in an iceboat in 30mph of wind). They *fly* through the wind, and it all works because of the resistance that keeps the blades/sail from blowing straight downwind. For a windmill, it's the fact that it's mounted to a solid stand. For a sailboat/windsurfer, it's the daggerboards or equivalent that stick down into the water, and on an iceboat its sharp runner keep the craft from moving sideways/downwind.

DSing itself isn't just about being blown downwind through the shear layer, and then coasting through the dead zone, or even being blown back up through the rotor. The turns at either end are converting the wind's kinetic energy into glider kinetic energy the same way the sails above do, but the resistive force is centripedal accelleration, 10-30 G's worth and that the wing is at a slightly higher angle of attack than the apparent wind throughout the turn. (I can't even begin to explain that more meaningfully, but I can visualize it so easily having been around both sailing craft and windmills for so many years).

In a good DS groove, you accellerate both at the top, while turning across the wind, and at the bottom turning across the rotor coming back up, and it coasts through the shear layer both up and down. If you were to try to build a windmill that could take advantage of this power generated by moving across the apparent wind at high speeds, I think it would be based more on this design
http://aerolab.virtualave.net/wind/1_5kvt.jpg
or one of
http://www.iwr.de/wind/tech/bilder/VERT_ROT.JPG
and you'd build it big enough that one side of it stuck up above the hill, and the other preferably way down into the rotor.

BTW, there's absolutely nothing preventing someone from building a shear layer paddle wheel with a wind block in front of it that simply blocks wind on half the paddles. The wind block doesn't have to be a hill. It can just be any big solid barrier. I'm sure it's been done, and the fact that it isn't in use, is a fair indicator that it's not a useful design. Pushing air or being pushed by air directly has never been efficient. Airfoils and the vortices they generate are where the power and efficiency come from.

ian

[Mark Wood]

Fascinating thread but I'm going to put it in DS where some of the DarkSiders can get some ideas in here now. :)

mw