Jet turbine like windmill

[Daox]

FloDesign Triples Efficiency of Traditional Wind Turbines| crispgreen.com

Its supposedly capable of producing the same amount of power as a turbine of twice the diameter and cost 40% less. Sounds like quite the deal. Just makes me wonder why someone didn't think of it earlier. It certainly looks cool though. Of course its still in testing.

Any of our windmill experts have any input?

[wyatt]

I am no expert, but I have seen other designs using a traditional style windmill and a huge venturi tube like setup to achieve (I believe) about twice the power from the same setup. Problems were the shroud/housing was expensive and there was a fear they could catch the wind and tip them over. I haven't looked much into those however...

[Ryland]

In the wind turbine design class that I took turbines that looked a lot like that were on the list of "scams that people loose money on" a normal three blade prop is getting around 40% of the energy out of the wind, if I remember correctly, so twice the diameter would be more then more then 3 times the area... right there is bad math, I think it was in the high 50's or mid 60% that the wind starts to go around the prop if you try to get to much energy out of it, the same would be true with a set up like this, it would just go around it.
this is not a new idea, it has been done, proven to not work.

[wyatt]

You get the highest efficiency per blade with the fewest number of blades (1 blade is the best on a "per blade" basis). If I remember correctly, the reason that you have 3 blades and not 2 or 4 (or more) is because of simple economics. Those huge blades are EXPENSIVE to build, but so is the rest of the windmill, so they do a simple trade and see where the least expensive design lays... 3 blades wins on large designs. I guess this is more of an FYI relating to the number of blades this design (and an older water pumping windmill) has. Any efficiency gains they see may be coming from the number of blades, not all from the housing...

[Ryland]

the number of blades makes it less efficient as it has more drag, each blade also creates turbulence behind it that affects the next blade, if you are going to have a whole bunch of blades like a turbine does then you need a set speed, for that you need to control the speed of the wind... good luck with that!
Yes, one blade is most efficient, but it is not stable, two blades is balance but it creates this weird gyroscope half the time when the blades are parallel, then when they are vertical that gyroscopic action disapeers almost 100% allowing it to twist, jump, shake and do whatever it wants in that moment... three blades make a stable wheel but they are also spaced out enough that they can act as air foils, like a wing, three of them are easy to adjust the pitch of, like you would with a wing for varied wind speed, all around three blades seem like a good idea, unless you want a drag device, like an old water pumping wind mill those blades act as drag devices, they are pushed by the moving air, they can never go faster then the air speed, a three blade prop can have the tips of the blades brake the speed of sound! it is an issue that has been delt with.

[Christ]

So I kind of wonder if there is any efficiency difference with bullet-nose cones in the middle of a turbine, etc... I also wonder if the airfoil design is really that much more efficient than just using a tilted blade at a fixed angle?

By "that much more efficient" I mean: Should I go out and buy a 3 blade plane prop to make a windmill, or should I just make 3 sticks from old boards with tapered edges and a fixed pitch to the wind?

[Ryland]

tilted chunks of wood will work for very low speed wind and the way the wind will make it spin is by pushing the blades out of the way... the only way they can move is around in a circle so they will move that way.
if you make your blades in to an air foil then your blades are air foils and fallow the same rules as wings fallow, their movement is based the same rules that create lift on a wing, I can't tell you if it is going to be 5 times more efficient or 30 times more efficient, but it's going to be many times better, not "a little better" check out Welcome to OTHERPOWER.COM because their home made stuff works.

Originally Posted by Christ

So I kind of wonder if there is any efficiency difference with bullet-nose cones in the middle of a turbine, etc... I also wonder if the airfoil design is really that much more efficient than just using a tilted blade at a fixed angle?

By "that much more efficient" I mean: Should I go out and buy a 3 blade plane prop to make a windmill, or should I just make 3 sticks from old boards with tapered edges and a fixed pitch to the wind?

[lichong712]

It looks very cool, creative invention.what is the outputs of your wind turbines? what kinds of materials you used?

[Bicycle Bob]

Originally Posted by Christ

So I kind of wonder if there is any efficiency difference with bullet-nose cones in the middle of a turbine, etc... I also wonder if the airfoil design is really that much more efficient than just using a tilted blade at a fixed angle?

By "that much more efficient" I mean: Should I go out and buy a 3 blade plane prop to make a windmill, or should I just make 3 sticks from old boards with tapered edges and a fixed pitch to the wind?

If you buy blades, get windmill parts. Airplane props would be the equivalent of flying a cambered wing upside down. If you don't mind some extra stress on the tower and bearings, you don't need precision blades, just longer ones. One fellow has some really crude-looking 4-blade designs that gain overspeed protection by the inherent aero properties of the inefficiencies existing.

[jhonebhrestom]

Actually real wind turbines are not designed like a fan, they are designed like a wing.
Wings on most airplanes are long and relatively skinny. For reasons that
someone else will have to explain to you, this us far more efficient than a
shorter, but fatter wing.Anyways i can guess this one as a mini wind mill.