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

Leo
"..So spoon-feed them pap if that's your style.."
That is of course how those who feel it beneath them to try and educate others in complex situations, but choose not to use analogies in order to convey the meaning better. Much better when others don't follow, simply because the lecture cannot convey the message/concept clearly, all this does is just provide a feeling of superiority. Doesn't help those wishing to learn..

"..There's no need for me to resort to hand-waving or analogies when setting up and inverting large matrices.."
If you were Stephen Hawking, I could understand that!

I haven't done high level maths for over 20 years, it is all way beyond me now. However i feel it rather sad that you only feel the need to invert matrices etc rather than exploring with your mind and/or the real world.

Perhaps that is why Schrodinger et al were geniuses, they went beyond numbers...

 

I think the waves when going direct to wind make it look faster. Yes, with pedal it is much faster. But its just a different thing all together. So it would not be fair to compare. The challenge is the main thing. It would be good if someone would start an Aeolus type competition on water. Maybe, this thread will encourage someone! In the eyes of the world they would see doing it on water as harder than doing it on land because there are two fluids involved and not hard land.

 

bil
We need a sponsor with enough interest to throw some good money at it.

I think competing can be done at a distance. Need some reasonable basis for comparison like covering a 10km course that covers all points of sailing and probably some independent body with worldwide reach to provide an observer for each attempt.

It would need a timeframe so that there is a deadline but something like 5 years to give time to develop. Attempts can be submitted at any time and the first attempt must be within say 3 years to qualify.

The key evidence for the record would be a GPS plot and wind data.

Should the prize be for the fastest in any conditions or a ratio of windspeed? I favour outright speed because this is a better test of durability.

I believe the Aeolus racers should do a circuit rather than a straight line course. Likewise with boats. It is no good being able to go well directly into the wind and be hopeless in all other directions. With my boat the most difficult in strong wind is reaching because I have limited ability to shift weight to keep the boat balanced.

Rick W

 

Adverse thrust rears it's ugly head again...

Rick

When you turn your turbine into a reaching condition you will notice there is a heeling moment introduced that is no different than what a sail produces. Sooner or later you will need to acknowledge that finding a way to eliminate the adverse component is ultimately the only solution.

Michael

 

Michael
It is not quite the same as a sail produces but certainly creates a heeling moment. It is really noticeable during variations in the wind. When the wind builds there is a lag before the boat speeds up and the force is much higher than when at the terminal speed. When the wind lulls there is a brief period where the force is in the reverse direction due to the momentum in the system and the turbine becoming a propeller. So in these way it is different to sail.

If you can build a system that can produce power without a force it will indeed be revolutionary.

Rick W

 

I had the same thing happen...

Rick

...when my free running bicycle/car did the same thing, running ahead with a leap then almost stopping dead when the adverse thrust hit, it oversped then lurched ahead when the turbine started acting like a prop.

Michael

 

My two bladed turbine gets over 80% efficiency once wind is above 4m/s. So I get a lot of power for the force on it. I expect your multi-bladed, cut pipe foils achieved much lower efficiency so there would be considerably higher force for the power developed.

With the simple turbi-prop set up it is the efficiency of the turbine and propeller that determine what speed it will get to in relation to windspeed. My turbine is about right for the boat but the prop I am using is really a bit small. Also without the ability to alter the gearing once operating it lacks flexibility to sail well on all points.

Rick

 

Not totally pipe sections...

Rick

My foils on my turbine were shaped very carefully to be pretty good foils except for the root area where they were almost a quarter of a circle. This gave it tremendous low speed torque, but this advantage vanished when it sped up. It was very hard to hold it back when it was standing still, and took off with a jump, but this hit the 'brick wall' at around 10-12 MPH. My bicycle chain drive couldn't shift gears while running, so I wasn't able to build up speed and then take advantage of the torque.

One time, when it got out of control it made a slow turn and went downwind pretty fast, too fast to catch it running and we had to jump in the truck and overtake it to stop it. I still haven't figured out how it was getting power at that point.

Michael

 

My son who videod the boat jokes a bit about the performance because when you hear the turbine spin up it is quite impressive, It sounds powerful and it is but the result is disappointing. The biggest problem is not being able to change gear to get more power from it once the boat is moving. So there is no doubt that gearing, by some means, is essential to get anywhere near the potential.

When I come back from my holiday I will take a video on the boat so you can get a better idea of the what the turbine is doing. This part of it is impressive.

Rick

 

My bike turbine idling...

This is a MPG of my turbine. That red tow bar was bent in a pretty steep arc when running, showing the conflicting forces that were keeping the speed down. It actually was spinning so fast when I took this picture you couldn't see the blades, but my shutter speed makes it look like it is barely turning.

Michael

 

Michael is that road noise or the turbine?

Did you see the close up video of my on-land test - attached again to this post. If you listen in the early stages you can hear the turbine accelerate in the gust. There is also another gust around the time you hear the neighbour hammering in the background.

I expect you would have got much better performance with fewer blades and and better foils. Your turbine will have quite a high power coefficient but relatively low efficiency.

The power coefficient is not all that critical as you can make the turbine just a bit bigger and get lots more power. The efficiency is critical because this sets how much power you will get for a given force at any particular windspeed. The "adverse" thrust that you have experienced is nowhere near as significant if the system efficiency is high.

Rick W

 

Taking a close look at this video and comparing the performance gives an idea of what is efficient. The comment on the the speed of the trike, using a multi-bladed turbine, highlights the problem with low efficiency:
http://www.youtube.com/watch?v=oOewm3IY6ag&feature=related

Even using a modern wind turbine made for fixed installations is not as good as a purpose designed turbine because the fixed turbines aim for the highest power coefficient. That is the wrong objective when the turbine is vehicle mounted.

Rick W

 

Adverse thrust made me wake up....

...to the problem, and I quickly realized that this approach was a dead end, that's why I didn't bother trying to optimize it. I could easily remove blades and make 4 or 2 bladed versions, but that would not solve the problem. I decided to look at the problem from a different perspective, and not try and 'Fight City hall' as the saying goes. Since air is a fluid, it is easier to make it flow in another direction so that the forces don't oppose the vehicle motion. In the new design, the power foils are at right angles to the direction of the wind, so they can't even create a force in that direction.

Michael

 

As noted before you have to prove that you can equalise the pressure on the inlet and outlet of the duct and also make up for all that extra external surface area that has to be forced through the air.

I accept there is a lot of energy in the air by virtue of the fact that it is nominally around 300K but I cannot see how you can extract any of this in your device.

Drawing an analogy to the L/D of a wing does not have any significance for what you are trying to achieve. The L/D is explained with momentum change of the airflow; nothing to do with heat energy in the air. There are minute temperature fluctuations as the air decompresses and compresses while flowing over the wing but the net result is an increase in temperature due to the friction of the air on the wing - as the previously linked paper records.

I expect you will need to come up with a simple demonstration or a scientifically based proof of the possibility before you will find a sponsor. The proof will having nothing to do with the L/D of a foil.

Rick W

 

Leo,
Thanks for posting that article, I enjoyed it. I remember when airfoils were explained in high school using the "2 particles that meet up" method. It didn't sit well with me and I asked why the particle will meet up on the other side but got an answer to the effect of "just because."


Here's my summary understanding of the article: airfoils provide lift because they curve the flow of air streams, and for air streams to curve there must be a pressure differential.

I don't suppose you know of a good article that explains why air wants to follow the curve of the top of the foil, do you? I appreciate how that article was honest about not trying to explain everything. It just said it has something to do with friction.


Now on a tangential note: if this is how foils work, it seems that this would apply to a highly rockered hull at higher speeds to provide negative lift and pull the boat deeper in to the water. I always understood it as the boat creating a bow wave which made a trough that the boat "fell" in to, and that may be the dominate force, but if it is curving the flow of water will that not also force the boat down, at least a little?