Betz' spinning in his grave (or is it vibrating...)

[fcfcfc]

Hi:

OK I see where you are going, but....

All right, try this. Lets take one fragment you mentioned of "forces" that engineers design to handle or go against, as you put it. How about the horizontal force on the HAWT which gets translated into a tension on one side of the tower and a compression on the other. Suppose we put 4 heavy compression springs at 90 degs 4 feet up from the base of the tower, pressing against it sideways. Now we hook a rod in the middle of each spring so that it is connected to a cam on the shaft of a little generator, and the other end to the tower shaft, another wards passing through the middle of the spring, much like a shock was connected through a spring on lets say a '69 Camero front end. Each of the springs can maybe compress 6", like heavy automobile spring. The pressure on those springs will be enormous due to the leverage the tower will have on them, and of course, the bottom of the tower is designed to let that movement occur. The gear ratio on the cam can be very high so even a small movement will create a rapid spinning of the generator(s). Now, the top of the tower and the HAWT will move around a bit, perhaps a few feet, as the wind blows from direction to direction. The generators will be spun as the spring(s) are compressed or releasing their stored up potential energy into kinetic energy.

Now the question I have for you is, do you think the energy you reap from the bottom gens is normally "lost" energy, or is it being subtracted from the HAWT spinning top energy, or some combination of the two..??..

.....Bill

[jacquesm]

yes, but that 'lost' energy comes out the budget that could have gone to moving your rotor / extraction device. The bookkeeping has to match:

100.0% - (total input power)

 40.7% - (betz tax)

mechanical losses -

electrical losses

= output power of the windpower extraction device

you are maybe able to recoup a couple of % of mechanical losses but you might actually just decrease your output power by the same amount.

The only thing that I can think of that would get a pretty efficient mill closer to the betz limit is a form of co-generation where you recoup some of your electrical losses as heat.

It's a fairly well known phenomenon in car design that any 'springiness' in the frame or suspension directly increases the required amount of fuel, that's a zero sum game.

I'd be as happy as anybody else if you found a way to break betz or get a mill that can operate near theoretical efficiency but I'm not going to hold my breath, my expectation would be that if you would test that side-by-side with a 'regular' setup that you would see the 'improved' version give you roughly the same power but out of two outlets instead of one. (assuming you're going to modify a regular machine with an additional device to 'recoup' vibration losses).

[bob golding]

i think Tesla did some work on resonance. might be worth having a look at

his conclusions.

cheers

bob golding

[DamonHD]

But the laws of thermodynamics have proven rather less negotiable for rather a long time!  B^>

[windstuffnow]

  So what your saying is, if you were extracting energy at the theoretical Betz limit then there wouldn't be any tower loading?

.

[jacquesm]

No, there would be plenty of tower loading, statically for the most part, and if the tower were vibrating due to the force on the blades being passed on to the tower (tower thump and so on) then that would come out of the 'after betz' budget.

There is also lots of pressure on the tower from the wind acting directly on the tower.

[DamonHD]

Kewl: I got a response from the inventor himself!

http://slashdot.org/comments.pl?sid=327505&cid=20985555

[Ungrounded Lightning Rod]

The area significant for Betz is "swept area" - the cross-section through which you're slowing down the air.

For this device it would probably be the area between the two bars supporting the ribbon.  If the ribbon were not supported by that duct it would be the area through which the ribbon vibrates plus a bit beyond it where it influences the air motion.

[Ungrounded Lightning Rod]

Case in point: The yard swing. A three year old can push an adult to incredible heights, every iteration through the swinging motion can add only a little bit to the total energy in the system, but because the 'spring action' of gravity allows the three year old to almost without loss recoup all the energy in the previous iterations you can 'lift' an adult to well over your normal abilities just with gentle pushes.

Which doesn't help you get more power out than is being put in.

When it's up to equilibrium the load (plus other losses) extracts as much power during each cycle as the prime mover injects.  The "adding up over many cycles" effect is useless.  The "energy recycled from one cycle to another" is a fixed amount of recirculating energy - part of your "capital equipment", like the magnetization of the permanent magnets - that participates in the mechanisms that make things work but can't be tapped (except maybe to extract some of it during shutdown).

For this device the power comes from the wind (slowing down the air flow in the process).  You never get more power out than the airflow lost by being slowed down.

[jacquesm]

> Which doesn't help you get more power out than is being put in.

I never meant to give that impression, my apologies if that was unclear.

The idea I tried to convey is that a lot of small inputs can be 'banked' and retrieved in one go (such as when you fall off te swing), not that the sum total is larger than the inputs.

[DamonHD]

He just me an email pointing to this Instructables thread:

http://www.instructables.com/forum/TZ7K4K6F7PCMVR3/

Rgds

Damon

[electrondady1]

thanks for the link.

it's a fascinating device.

i think it could scale up too .

if your ever on a sail boat in a storm there are a lot of vibrating ropes.