Windmill or Wind Turbine- powered boats: how many are out there, and are they viable?

[Boston]

Rick in reference to your post 263

been reading along for a while now
you guys might check out these ducted ( sorta ) turbines



here's one thats a little more advanced



this is a good side by side comparison showing some clear advantages to a vertical orientation



and the helical configuration also has an aesthetic appeal the others dont

were this last also ducted it seams it would be the winner in performance and visual appeal

[Guest625101138]

Originally Posted by Demiurg

.
nVtot = 20%.
nVv = 23%.

You do the math...
Carl

If you discount the electrical losses it is almost identical to my 28% power recovery coefficient for the 4m diameter prop. Not sure what point you are making. You seem to be agreeing with my numbers.

Rick W

[Demiurg]

Originally Posted by Rick Willoughby

If you discount the electrical losses it is almost identical to my 28% power recovery coefficient for the 4m diameter prop. Not sure what point you are making. You seem to be agreeing with my numbers.

Rick W

I think we are coming from quite different technical angles... You are a mechanical engineer, right? And I am an all out electrics buff...
28 percent recovery (I would write efficiency (potatos, potatoes)) is pretty good actually without CAD/CAMed wing-panes.
I saw that you like to supercharge with ducting, take a look at the verticel seriously ducted postbetz turbine at www.energytower.se there are some old swedish television movies of an old prototype under PRESS. It's in swedish, but the pictures speak for themselves. They've pretty much stumped the industry with their measurements and I didn't believe it untill I took a closer look and did my own measurements.
I know, it is electric, but you could as well use the idea in mechanics if you construct a flexible spindle (or whatever it is called in mechanical english;-)
The best part is that they are so sillily safe that you can mount them in cities, even in safety crazy Sweden.

Regards
Carl

[Demiurg]

Here is a YoTubber-link for a Swedish Television segment about Energytower.
There is a short translation text there. On error though, it leans at 15 degrees.

http://www.youtube.com/watch?v=DS6LJb3gHNg

Regards
Carl

[Boston]

the counter rotating vawt's are something to take a look at
this one doesnt have fins
but I think I saw one that did
if I find it Ill post it



course this one was kinda cool as well even if less efficient

[Guest625101138]

Originally Posted by Demiurg

... You are a mechanical engineer, right? And I am an all out electrics buff...

Carl

No. I am an electrical engineer with many years experience at design and engineering management level in many facets of engineering through research and development projects.

Rick W

[Demiurg]

Originally Posted by Rick Willoughby

No. I am an electrical engineer with many years experience at design and engineering management level in many facets of engineering through research and development projects.

Rick W

I stand corrected, the same here.

Carl

[Lin Olen]

The Betz Law applied to early Dutch type windmills close to ground. It does not apply to Rotary Sails or aircraft airscrews which easily approach 80% plus.
Think of subsonic air as an incompressible fluid, if this was not so voice could not be transmitted to the ear. Rotary Sails approach airscrew efficiencies and effectiveness. Best application requires variable pitch blades to reduce spinnaker effect as speed increases. A great deal of "science" is untrue. Cheers, Lin.

[Demiurg]

Originally Posted by Lin Olen

The Betz Law applied to early Dutch type windmills close to ground. It does not apply to Rotary Sails or aircraft airscrews which easily approach 80% plus.
Think of subsonic air as an incompressible fluid, if this was not so voice could not be transmitted to the ear. Rotary Sails approach airscrew efficiencies and effectiveness. Best application requires variable pitch blades to reduce spinnaker effect as speed increases. A great deal of "science" is untrue. Cheers, Lin.

Hello Lin!

A question here, with rotary sails, do you mean flettner-rotors or any other magnii-effect or do you mean cousteau-like sails? Or are you talking about actual rotary sails? Or are we talking about VAWTs (vertical axel wind turbines)? Because as we both of course know the ordinary airscrew can't post-B, never have, and never will. About Post-B, read down-stairs.

Yes, I can think of air as an incompressible fluid. But I don't need to. Air is not an imcompressible fluid, it is a particle dynamic medium. Since you can compress air you will get problems with thinking about it as imcompressible, the fallacies will get quite spectacular in some off-corner problems. For instance ET uses the decompressabiltiy of air to go post-B. Think about it for a while.
But I do understand your point:-)

Oh I know that you can "break" Betz, but very few have actually done so.
Currently on the market there is no known pneumo-electrical plant that is post-B. Albeit, I might have missed some small company out in the great blue yonder:-)
There has been a lot of talk in the industry conferences about post-B plants during the last five years and some of the smaller companies have tried. Some with good technical succeses. But they have been vastly impractical and to expensive to start production of. My former company was on the look-out for good post-B ideas that was productionable, but never found any.

The old engineering truth, "just because something is doable doesn't mean it is practical" has probably never been more true. And than we all have all of the bull-shiters and scamers... I've seen about fifty pure scams and bull-shits over the years that has claimed that they can go post-B. As soon as I pulled out my own measuring devices they all disapeared. Wonder why I am sceptical and cynical?

All new post-B plants must meet these minimum criteria, besides being vastly more efficient to be economically viable:
1. Be as safe or safer than the current technology. I would say that if it isn't safer than mills it is out after the last couple of disasters.
2. It must be a maximum of 25 percent more expensive than todays mills.
3. They must be more quiet.
4. They must be simpler to service and have fewer moving parts, and no gearbox.
5. They must be able to work in a much greater span of winds.

After I exited "the allmighty colossus of wind" I went to the only known company with working practical post-B plants and now we are well into pre-production with production starting Q1-10.

Regarding science, it is a warning sign when people start arguing WITH the concept of science, instead science loves new and TESTABLE data that is REPEATABLE and refutes known concepts.

Regards
Carl

[Boston]

thought this article might interest some of you folks

ScienceDaily (Jan. 26, 2009) — Inspired by the aquatic wriggling of beetle larvae, a University of Pittsburgh research team has designed a propulsion system that strips away paddles, sails, and motors and harnesses the energy within the water's surface. The technique destabilizes the surface tension surrounding the object with an electric pulse and causes the craft to move via the surface's natural pull.

The researchers will present their findings Jan. 26 at the Institute of Electrical and Electronics Engineers' 2009 Micro Electro Mechanical Systems (MEMS) conference in Sorrento, Italy.
This method of propulsion would be an efficient and low-maintenance mechanism for small robots and boats that monitor water quality in oceans, reservoirs, and other bodies of water, said Sung Kwon Cho, senior researcher and a professor of mechanical engineering and materials science in Pitt's Swanson School of Engineering. These devices are typically propeller-driven. The Pitt system has no moving parts and the low-energy electrode that emits the pulse could be powered by batteries, radio waves, or solar power, Cho added.
Cho envisioned the system after reading about the way beetle larvae move on water, he said. Like any floating object, larva resting in the water causes the surface tension to pull equally on both sides. To move forward, the larva bends its back downward to change the tension direction behind it. The forward tension then pulls the larva through the water.
Cho and his team-Pitt engineering doctoral students Sang Kug Chung and Kyungjoo Ryu-substituted the larva's back bending with an electric pulse. In their experiments, an electrode attached to a 2-centimeter-long “mini-boat” emitted a surge that changed the rear surface tension direction and propelled the boat at roughly 4 millimeters per second. A second electrode attached to the boat's front side served as the rudder.

An abstract of Cho's mechanism is available on Pitt's Web site at http://www.pitt.edu/news2009/Cho.pdf.

[Richard Atkin]

1. FloDesign's wind turbine extracts 3 to 4 times as much energy from the wind as a typical long blade turbine?

False claim?

2. On a yacht at sea, how much energy is extracted from a typical wind by a typical vertical screw turbine compared to a typical long blade turbine, considering the effects of pitch and roll. Could be interesting.

[Richard Atkin]

I forgot to mention that all considered turbines would weigh the same.

[Windmaster]

I'd like to hear where a vertical screw turbine has been used at sea? As far as I know one never has. They have for ancilliaries such as battery top up for navigation etc. but not for primary power.

[backyardbil]

Those with horizontal axis are probably more efficient. Does anybody know what tip speed ratio would be best?

[Boston]

the virtical turbines are definitely more efficient in any wind condition
optimal wind speed would depend on the configuration of the windings
there is a company called Windblue power that sells custom windings cheep for these type of DIY turbines
no I haven't tried building one yet but they seem pretty straight forward