turbineless wind-power

[darkbeaver]

There is a lot of kinetic energy there and all kinetic energy eventually turns to heat at some point, but I have no idea how it might be harnessed.

I 'v been thinking a bit about this gizmo since I saw it this fall. If the wing/sail were fluid filled with coolant and a circulating system supplied to bleed the heat into an accumulator and then step it up with a heatpump. Alternately why not just circulate the heat into a sink such as a floor?

 

[s243a]

I really don't think this concept will scale up well. I see it more as an application for remote areas with low power requirements. That said if it is going to be scaled up the tension probably needs to be increased because if the flapping part is in greater tension then it should be able to lift a greater load.

 

[s243a]

If people are going to play with this then here is some information:

n dimensional analysis, the Strouhal number is a dimensionless number describing oscillating flow mechanisms. Often, it is given as:

where St is the dimensionless Strouhal number, f is the frequency of vortex shedding, L is the characteristic length (for example hydraulic diameter) and V is the velocity of the fluid.
For spheres in uniform flow in the Reynolds number range of 800 < Re < 200,000 there co-exist two values of the Strouhal number. The lower frequency is attributed to the large-scale instability of the wake and is independent of the Reynolds number Re and is approximately equal to 0.2. The higher frequency Strouhal number is caused by small-scale instabilities from the separation of the shear layer (Kim and Durbin, 1988 and Sakamoto and Haniu, 1990).

http://en.wikipedia.org/wiki/Strouhal_number
You want to design it so that the resonant frequency of the flapping thing is close to the frequency of the vortex shredding.

I think for the Characteristic length you use the hydraulic diameter:

Hydraulic diameter

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It has been suggested that this article or section be merged into Frictional pressure drop. (Discuss) The hydraulic diameter, Dh, is a commonly used term when handling flow in noncircular tubes and channels. Using this term one can calculate many things in the same way as for a round tube.
Definition:

where A is the cross sectional area and U is the wetted perimeter of the cross-section.
For a round tube, this checks as:

http://en.wikipedia.org/wiki/Hydraulic_diameter
http://en.wikipedia.org/wiki/Reynolds_number

For the natural frequency of the flapping part use:

Frequency of the wave

Once the speed of propagation is known, the frequency of the sound produced by the string can be calculated. The speed of propagation of a wave is equal to the wavelength λ divided by the period τ, or multiplied by the frequency f :

If the length of the string is L, the fundamental harmonic is the one produced by the vibration whose nodes are the two ends of the string, so L is half of the wavelength of the fundamental harmonic. Hence:

where T is the tension, μ is the linear mass, and L is the length of the vibrating part of the string. Therefore:

• the shorter the string, the higher the note
• the higher the tension, the higher the note
• the lighter the string, the higher the note

• http://en.wikipedia.org/wiki/Vibrating_string

And to make this completly self contained

For the common case of a homogenous substance of length L and total mass m, this simplifies to:

The term linear density also refers to how dense a line is drawn.

http://en.wikipedia.org/wiki/Linear_mass

 

[Tonington]

I really don't think this concept will scale up well. I see it more as an application for remote areas with low power requirements. That said if it is going to be scaled up the tension probably needs to be increased because if the flapping part is in greater tension then it should be able to lift a greater load.

Indeed, the concept wasn't intended for something which can be scaled up. It was designed for micro applications, because the turbines don't scale down very well.

 

[darkbeaver]

Indeed, the concept wasn't intended for something which can be scaled up. It was designed for micro applications, because the turbines don't scale down very well.

I have a very small axial flux turbine that I'm building from a modified hard drive. What's the problem you're talking about with scaling turbines down?

 

[Tonington]

I have a very small axial flux turbine that I'm building from a modified hard drive. What's the problem you're talking about with scaling turbines down?

The conventional turbines are expensive. The cost makes them prohibitive for the poverty stricken developing rural areas of this world. Perhaps you should market yours to the less fortunate folk Beav. :smile:

 

[s243a]

Conventional wind turbines don’t scale down well—there’s too much friction in the gearbox and other components. So poor, remote communities don’t have any way to harness the power of the wind. Till Shawn Frayne, a 28-year-old inventor based in Mountain View, Calif., saw the need for small-scale wind power to juice LED lamps and radios in the homes of the poor. Frayne’s device, which he calls a Windbelt, is a taut membrane fitted with a pair of magnets that oscillate between metal coils. Prototypes have generated 40 milliwatts in 10-mph slivers of wind, making his device 10 to 30 times as efficient as the best microturbines. Popular mechanics has a good article about the device here.

http://www.thingsaregood.com/tag/wind-power/

 

[s243a]

Here is another link on the windbelt.
http://www.popularmechanics.com/technology/industry/4224763.html?series=37

Here's some interesting responses to the idea:

105. RE: Windbelt, Cheap Generator Alternative, Set to Power Third World
I'm not that impressed. 50 milliwatts is nothing. I have a propeller generator that will produce more power in low wind. There is not enough room fot the magnet to travel to develope usable power. Nothing will become of this. Lets have some details, how many volts at how many amps, under what conditions.

78. some really stupid commenters
Do people have any idea what 0.04 Watts at 10 mph means? It's a *micro*power device! When you need 100 Watts, get a wind turbine for $500, not several thousand of these. And fools who propose sticking these on cars (which already have huge alternators and 12V outlets) or next to laptop fans (which already have batteries and powered USB ports)... learn about conservation of energy.


67. Great!
This is a vary cool idea! Not only that but its well thought out. (All credit to Wikipedia for without it I could not argue a valid point) The point "it doesn’t generate much energy" keeps popping up, so ill see if I can put some facts into the fight. The power available in the wind is given by: (for a Turbine) P = 0.5A Rho r^2 V^3 Where: P = power in watts, A = efficiency constant, Rho = mass density of air in kilograms per cubic meter, (Mass density is worked out as – Rho = Mass / volume) r = radius of the wind turbine in meters, V = velocity of the air in meters per second. So for R=30 Meter's (average inland turbine blade radius) V = 10 mph (16 km/h or 4.5 m/s) (The average speed at wind farms) Rho = 1.225 (At 15*C at sea level) A = 30% (because I don’t know the true figures here I am using a figure someone mentioned earlier) P = 0.15*1.225*900*91.125 = 15069 watts (15Kw or 15,069,000 milliwatts) For the Wind Belt Looks to measure about 80 CM * 10 CM * 10 CM or there about’s Apparently generates 40 milli watts at 10 mph So in its current state if you built a wall out of them 80 meters across and 60 meters high (to match the un-usable area of a turbine) you would generate Number of units = 60000 (80 meters / 10 CM) * (60 meters / 80 CM) 40Milliwatts * 60000 units = 2,400,000 milli watts So to conclude, no it doesn’t generate as much power as a turbine. But Its easier to repair, and requires less land to be dedicated to its use, its cheaper and its user friendly. A good product for an unexplored market


19. RE: Windbelt, Cheap Generator Alternative, Set to Power Third World
Website: http://ww.com/
I'm sorry but this device is not 10 to 30 times better than then the best microturbines, which are over 20% efficient. Betz' limit is not about to be crossed, no matter whether it is with rotating or vibrating devices. I predict this invention will not 'break' because it it tuned to only a narrow range of windspeeds and wildly inefficient compared to modern rotary machines. Nice try though !

 

[#juan]

Seems to me we are making something very simple complicated. Four or five decades ago(or more) my dad built a windmill on the farm that produced enough power to run a radio and a few light bulbs

http://www.poormansguides.com/index3.htm

 

[s243a]

Here's another interesting link:
http://www.humdingerwind.com/windbelt.html

I found this link on the hummingbird sight:
http://www.humdingerwind.com/docs/ApplPhysLett_priya.pdf

It discusses small scale wind power.

 

[s243a]

Jeaun I'm not sure the poor mans windmill you describe will work at the windspeeds this is intended to work at:

Small scale energy harvesting from wind flow has always
been the aspiration of community for several applications
including wireless sensor networks for border intrusion
monitoring and weather stations, lighting inside tunnels and
remote locations, and power sources for recharging battery.
The challenges associated with small scale electric energy
generation are as following:
i conversion of the random
wind flow into periodic mechanical ac stress,
ii realization
of significant magnitude of stress

0.5 N,
iii enhancing
the frequency of the stress cycle

5 Hz, and
iv light
weight and cost effectiveness. The wind speeds of interest
are in the range of 3–10 miles/h. At these speeds the force
generated from small size vanes having surface area of
2–5 in.2 is very small
0.1 N, which makes the use of any
kind of electromagnetic converter or “dynamo” difficult.
the force required for full deflection is small, the
charge developed under fully loaded condition is high, the
resonance frequency is quite low, and the manufacturing cost
of bimorph is very low.

http://www.humdingerwind.com/docs/ApplPhysLett_priya.pdf

 

[Tonington]

What do you think of this one s243a? It's a little light on details, actually very light on details.

 

[s243a]

What do you think of this one s243a? It's a little light on details, actually very light on details.

For home power there is now comparison. The link you gave says the power output is 1.2kW. That could power a lot of light bulbs. However, the device you linked to is probably more expensive and won't work at as low a wind speed.

 

[warrior_won]

When I saw the title of this thread, I thought it was going to be a joke. I thought you were going to say, "Turbineless wind power: Blowjob".

That's how women get things done, right?

 

[#juan]

Jeaun I'm not sure the poor mans windmill you describe will work at the windspeeds this is intended to work at:

http://www.humdingerwind.com/docs/ApplPhysLett_priya.pdf

The windmill my dad made was not the one in the link. Admittedly, my dad's windmill probably didn't turn very fast or produce any power at 3mph wind speed but at ten or fifteen mph it did fine. I very much doubt if any of them produce a lot of power from 3 mph winds.

 

[darkbeaver]

The windmill my dad made was not the one in the link. Admittedly, my dad's windmill probably didn't turn very fast or produce any power at 3mph wind speed but at ten or fifteen mph it did fine. I very much doubt if any of them produce a lot of power from 3 mph winds.

3mph is a lot of power spread over a schooners sail are though, that's a lot of force if you can harvest with verticle axis machines

 

[darkbeaver]

The windmill my dad made was not the one in the link. Admittedly, my dad's windmill probably didn't turn very fast or produce any power at 3mph wind speed but at ten or fifteen mph it did fine. I very much doubt if any of them produce a lot of power from 3 mph winds.

3mph is a lot of power spread over a schooners sail area though, that's a lot of force if you can harvest with verticle axis machines,