Vertical Wind Turbine - better than you might think

louis · 2021-04-19 18:34:04

Interesting video on a vertical wind turbine that can capture wind energy from traffic and low force prevailing winds.

Might have application on Mars as well, I'm thinking where the wind force is very low.

https://www.youtube.com/watch?v=gcSnwW5v3f8

Last edited by louis (2021-04-19 18:34:31)

SpaceNut · 2021-04-19 19:19:31

Thanks for the wind video as it reminded me of all the types there are from the many DIY builds that I have seen.
This is a life support function to create power....

here are those that we have
Wind power : possible ?

This one makes use of up draft as caused by heat to cause the wind to move
Solar chimeys - Feasible?

The video starts out with a prop of what the large gear driven hillside units are followed by the split barrel drum and others....

Calliban · 2021-04-20 07:54:59

However the wind turbine is made, its power output is limited by the kinetic energy of the wind that passes through its blades.

W = 0.5 x n x A x rho x v^3

n = efficiency - the maximum achievable beings the Betz limit.
A = swept area of blades
Rho = 0.02kg.m-3 (varies with height and temperature)
V = airspeed (m/s)

Efficiency is a variable that is a function of design. Air speeds can be maximised through suitable siting. Increasing swept area increases the amount of power that an individual turbine can produce, at the expense of making it bigger and taller. Rho is set by nature.

Generally on Mars, power output per unit area will be much lower than on Earth due to the low density of Martian atmospheric gases.

Last edited by Calliban (2021-04-20 08:52:59)

tahanson43206 · 2021-04-20 08:40:48

For Calliban re #3

SearchTerm:Turbine wind - design considerations in general and for Mars in Particular see #3 above
SearchTerm:Wind turbine design equation with explanation

(th)

Quaoar · 2021-04-20 13:30:29

tahanson43206 wrote:

For Calliban re #3
SearchTerm:Turbine wind - design considerations in general and for Mars in Particular see #3 above
SearchTerm:Wind turbine design equation with explanation
(th)

An evolution is the bladeless vertical Tacoma Vortex, which oscillate in the wind moved by Von Karman vortex.

https://www.youtube.com/watch?v=Mf-gps4r2L0

tahanson43206 · 2021-04-20 13:58:55

For Quaoar re #5

Thank you for that inspiring video link!

It shows a way of making energy when sand storms are in progress, assuming the fabric can be made resistant to iron oxide dust.

This is an energy source that would work day or night, independent of solar flux.

Nice!

SearchTerm:tower wind energy catcher Quaoar #5 above
SearchTerm:wind energy no moving parts (exposed to the outside)

There has to be an energy production mechanism at the base of the tower, but it would (presumably) be protected from the weather.

I'll be quite interested to see what the forum may think of that idea.

(th)

RobertDyck · 2021-04-20 14:09:09

For Earth, I prefer helical wind turbines aka helical windmills. These work with changing wind direction: north, south, east, west, or even up. This is ideal for urban environments where buildings cause gusting wind to constantly change direction. The idea is a house with solar panel roof, windmill in back yard, batteries in the basement, geothermal heat pump (aka ground source heat pump), well insulated, heat exchanger, and passive solar. All designed into one house. Also use LED lights, and high efficiency appliances. Result: the house will never EVER purchase power from the grid. Designed to be 100% energy independent during worst case weather conditions for that area. The rest of the year (the other 51 weeks) the house will sell power to the grid. So the power utility will never send the home owner a bill, only a cheque. Or more likely direct payment to the owner's bank account, with an email statement.

From the utility's point of view, reversing power flow is a nightmare. However, these homes will not do that. Power will flow in one direction only: from private homes to the grid. Entire neighbourhoods could be built this way, the power utility would consider them to be a power farm.

Some people have argued if everyone does this, then who buys the power? But this doesn't work for tower buildings: downtown office towers or apartment towers. This only works with low buildings with substantial roof: houses, shopping malls, even most schools. And industry will always be hungry for power. So there will be a market.

On Mars? Well, the issue is how much power could you really get?

louis · 2021-04-20 15:12:33

I was wondering whether we could maximise wind force on Mars by creating tapered tunnels or gorges, so wind force is concentrated at the end of the narrowing tunnel or canyon - with the wind turbines sited at the narrow end. Would that work?

Last edited by louis (2021-04-20 15:13:13)

Calliban · 2021-04-20 15:22:00

louis wrote:

I was wondering whether we could maximise wind force on Mars by creating tapered tunnels or gorges, so wind force is concentrated at the end of the narrowing tunnel or canyon - with the wind turbines sited at the narrow end. Would that work?

Yes. If you find a canyon with the right orientation to funnel the westerly winds. But a better question would be, will it increase wind speed enough to overcome the limitations imposed by very low atmospheric density? Why don't you read up on compressible fluid dynamics and work out what sort of velocity increase is likely to occur? You can then use the equation I gave you earlier to work out power per unit of swept area and compare it to typical values on Earth.

I think you will probably find that very high wind speeds are needed for this to produce comparable energy per unit swept area. It might work in the sort of speeds prevalent in dust storms.

Last edited by Calliban (2021-04-20 15:25:18)

louis · 2021-04-20 17:08:37

Why don't you read up on compressible fluid dynamics?

Alternatively I could pull out my teeth with pliers! lol That's why we have engineers - so people like me (the sort of philosophically minded person who asks why in a physics undergraduate primer they reference "force" about 10,000 times without ever actually defining what it means!) don't have to.

But yes, I was thinking with higher wind force during dust storms this might be a useful addition to energy generation. The only reason I would think it worthwhile really is that the devices seem simple and cheap to make and to install. They could probably be made robotically in the thousands with far less effort that would go into manufacture of either PV panels or a nuclear reactor.

Calliban wrote:

louis wrote:
I was wondering whether we could maximise wind force on Mars by creating tapered tunnels or gorges, so wind force is concentrated at the end of the narrowing tunnel or canyon - with the wind turbines sited at the narrow end. Would that work?
Yes. If you find a canyon with the right orientation to funnel the westerly winds. But a better question would be, will it increase wind speed enough to overcome the limitations imposed by very low atmospheric density? Why don't you read up on compressible fluid dynamics and work out what sort of velocity increase is likely to occur? You can then use the equation I gave you earlier to work out power per unit of swept area and compare it to typical values on Earth.
I think you will probably find that very high wind speeds are needed for this to produce comparable energy per unit swept area. It might work in the sort of speeds prevalent in dust storms.

SpaceNut · 2021-04-20 18:20:32

louis wrote:

I was wondering whether we could maximise wind force on Mars by creating tapered tunnels or gorges, so wind force is concentrated at the end of the narrowing tunnel or canyon - with the wind turbines sited at the narrow end. Would that work?

Wind and terrain use are the same on earth just with a denser working fluid so yes even on Mars.

SpaceNut · 2021-04-20 18:23:58

RobertDyck wrote:

On Mars? Well, the issue is how much power could you really get?

This is dependent on the design mass of the props materials used, rolling resistance to the wind caused motion and the friction of the generator that gets attached to the prop..

RobertDyck · 2021-04-20 18:43:15

Ingenuity helicopter has counter rotating blades, so wash from top blades increases air velocity over lower blades. And blades rotate at 2400 rpm. Helicopters on Earth rotate 450-500 rpm. I would like to see some math showing how much power can be generated. What wind exists on Mars, how much power over a typical month.

Oldfart1939 · 2021-04-20 22:34:18

The effect terrain has on wind flow is, in aviation circles, is called MECHANICAL TURBULENCE when an aircraft gets bumped around by ground effects. I experienced this a LOT in the Casper, Wyoming area. It can be very significant and has caused accidents with extremely light planes.

SpaceNut · 2021-04-21 19:30:12

https://sciencing.com/average-wind-speed-mars-3805.html

Viking sites, the average wind speed registered at 2 to 7 meters per second (5 to 16 mph) during the Martian summer. During the fall, the average wind speed increased to 5 to 10 meters per second (11 to 22 mph). Across the year, the wind speed on Mars averaged 10 meters per second (or 22 mph).
wind speed on Mars can reach up to 17 to 30 meters per second. The maximum speed of 30 meters per second (60 mph) was observed during a dust storm at the Viking site.

https://www.grc.nasa.gov/WWW/K-12/WindT … rmula.html
https://hummingbird.arc.nasa.gov/Public … copter.pdf

https://www.sciencedirect.com/science/a … 4216301724

https://byjus.com/wind-energy-formula/

https://www.rpc.com.au/pdf/wind4.pdf

https://science.howstuffworks.com/envir … urbine.htm

http://www.m-hikari.com/ams/ams-2012/am … 2-2012.pdf

http://www.ijsrp.org/research_paper_feb … 012-06.pdf

SpaceNut · 2021-04-22 18:36:27

https://www.semprius.com/how-much-power … e-produce/

Figure-2-wind-turbine-1-kw-schematic-power-curve-1024x576.jpg.webp

Typically shut-down speeds are about 25 m/s.
To put these speeds in perspective, maximum power is at about 11 m/s which is 24.6 mph or 21 knots. Pretty windy. A shut-down wind speed of 25 m/s is 56 mph or 48.6 knots. This shows that wind turbines have a wide operating window for stronger winds. At the lower end, a minimum wind speed of about 5 m/s is often considered necessary for a wind turbine to be viable. This is 11 mph or 9.7 knots.
Wind turbines work by converting the wind that passes through the spinning turbines into energy. They’re about 40-50% efficient at doing this. The spinning turbines define a circle, with wind passing through the area of the circle being converted to energy. Remembering some basic high school maths, the area of a circle is pi x r2. In this case r is the length of the turbine blades.

https://www.energy-xprt.com/articles/do … ter-669025

louis · 2021-04-22 18:44:17

I seem to recall a figure of the wind force for any given speed being, on Mars, 1/20th of that on Earth and it's wind force, not speed per se that drives turbines.

SpaceNut wrote:

https://sciencing.com/average-wind-speed-mars-3805.html
Viking sites, the average wind speed registered at 2 to 7 meters per second (5 to 16 mph) during the Martian summer. During the fall, the average wind speed increased to 5 to 10 meters per second (11 to 22 mph). Across the year, the wind speed on Mars averaged 10 meters per second (or 22 mph).
wind speed on Mars can reach up to 17 to 30 meters per second. The maximum speed of 30 meters per second (60 mph) was observed during a dust storm at the Viking site.
https://www.grc.nasa.gov/WWW/K-12/WindT … rmula.html
https://hummingbird.arc.nasa.gov/Public … copter.pdf
https://www.sciencedirect.com/science/a … 4216301724
https://byjus.com/wind-energy-formula/
https://www.rpc.com.au/pdf/wind4.pdf
https://science.howstuffworks.com/envir … urbine.htm
https://resize.hswstatic.com/w_290/gif/ … bine-1.jpg
http://www.m-hikari.com/ams/ams-2012/am … 2-2012.pdf
http://www.ijsrp.org/research_paper_feb … 012-06.pdf

GW Johnson · 2021-04-23 17:51:57

"I seem to recall a figure of the wind force for any given speed being, on Mars, 1/20th of that on Earth and it's wind force, not speed per se that drives turbines."

That "1/20" factor is utter BS. This is rather basic physics. The force on any given element of a blade on a rotating windmill is the wind pressure ("dynamic pressure") times the element area times the element lift coefficient (a number that can be positive or negative depending upon angle of attack), but that peaks at a stall magnitude in the 1 to 1.5 range. The dynamic pressure is 0.5 times density times velocity squared. Blade element drag is similar, but trends differently with angle of attack, and does not peak, it just gets larger and larger.

The two forces element lift and element drag combine to create an axial force and a force tangential to the rotational motion. This is just vector addition, and vector resolution of components, which any person who passed high school physics should understand. You have to integrate (yep, calculus is involved!!) the product of radius and tangential force from hub to tip of each blade, (and sum for all blades), to get the torque of the blading system. There is no difficulty with that, as long as you understand that integral calculus is a way to sum up contributions when the formulas are not simple.

If the blade torque sum exceeds the shaft drag torque sum, the rotation rate accelerates. When it does not, the rotation rate decelerates. There is usually (but not always) a rotation speed where blade torque equals shaft drag torque (the torque required to drive a generator, for example). That is the steady (equilibrium) operating speed for the windmill.

Density on the surface of Mars is 0.007 (0.7%) that on the surface of Earth, typically. For the same wind speed, the wind pressure will be in the same 0.7% ratio to that on Earth, not some 1/20 = 0.05 = 5% that on Earth. You cannot argue with that. For the same distribution of blade twist, the same distribution of blade element angles of attack will exist at the same radius. Thus the same distribution of blade element lift and drag coefficients will exist, along each blade.

If so, then torque on Mars will be 0.7% torque on Earth, all else equal. Not 5% = 1/20 that on Earth.

GW

louis · 2021-04-23 18:42:58

Keep your hair on, as we say over here. Was only trying to remember and correct the misleading impression being given that wind speed is the main issue.

Whilst your figures are no doubt correct there are two points to be made.

Firstly that atmospheric pressure varies on Mars - there is no sea level equivalent. Hellas Planitia is twice the average.

Secondly the gravity being 38% of Earth's, means the effective ability of the Mars wind to move a turbine is much higher all else being equal (which it isn't, granted). So that would mean that at Hellas Planitia 12.4 mb would in effect be giving you the same force you would get at 32.6 mb - 3.26% of the Earth's atmosphere, 1/30th the strength of the wind on Earth.

I'm certainly not a strong advocate of wind energy on Mars. But it does seem possible that one could do it, maybe using my idea of topograpical focussing of the wind force, which I haven't seen discussed elsewhere to increase the output.

GW Johnson wrote:

"I seem to recall a figure of the wind force for any given speed being, on Mars, 1/20th of that on Earth and it's wind force, not speed per se that drives turbines."
That "1/20" factor is utter BS. This is rather basic physics. The force on any given element of a blade on a rotating windmill is the wind pressure ("dynamic pressure") times the element area times the element lift coefficient (a number that can be positive or negative depending upon angle of attack), but that peaks at a stall magnitude in the 1 to 1.5 range. The dynamic pressure is 0.5 times density times velocity squared. Blade element drag is similar, but trends differently with angle of attack, and does not peak, it just gets larger and larger.
The two forces element lift and element drag combine to create an axial force and a force tangential to the rotational motion. This is just vector addition, and vector resolution of components, which any person who passed high school physics should understand. You have to integrate (yep, calculus is involved!!) the product of radius and tangential force from hub to tip of each blade, (and sum for all blades), to get the torque of the blading system. There is no difficulty with that, as long as you understand that integral calculus is a way to sum up contributions when the formulas are not simple.
If the blade torque sum exceeds the shaft drag torque sum, the rotation rate accelerates. When it does not, the rotation rate decelerates. There is usually (but not always) a rotation speed where blade torque equals shaft drag torque (the torque required to drive a generator, for example). That is the steady (equilibrium) operating speed for the windmill.
Density on the surface of Mars is 0.007 (0.7%) that on the surface of Earth, typically. For the same wind speed, the wind pressure will be in the same 0.7% ratio to that on Earth, not some 1/20 = 0.05 = 5% that on Earth. You cannot argue with that. For the same distribution of blade twist, the same distribution of blade element angles of attack will exist at the same radius. Thus the same distribution of blade element lift and drag coefficients will exist, along each blade.
If so, then torque on Mars will be 0.7% torque on Earth, all else equal. Not 5% = 1/20 that on Earth.
GW

kbd512 · 2021-04-23 22:18:24

According to the Viking lander atmospheric measurements, average Mars sea level atmospheric density is 0.02kg/m^3.

That's 1/50th of Earth sea level atmospheric density.

As long as we're talking about unconventional wind turbines, has anyone considered the EWICON?

Since it doesn't have any moving parts and the dust on Mars does such a good job of generating static electricity, may this is worth developing further?

Windenergy convertor EWICON animation, TU Delft

Calliban · 2021-04-24 03:22:26

Louis, the lower gravity of Mars does not increase the kinetic energy in its winds. This is a function of wind speed and air density.

W = 0.5 x n x A x rho x v^3.

Let's say average winds peed of 7m/s and efficiency 40%, which is 80% of the Betz limit. Rho = 0.02kg/m3.

W= 0.5 x 0.4 x 1 x 0.02 x 7^3 = 1.37W/m2 of swept area.

A wind turbine with blade diameter 100m, would generate 10.8kW. Not a good net energy return I would suggest.

louis · 2021-04-24 06:06:30

To reiterate I'm not advocating here but I have read a little on the subject. Specifically I saw it stated that the the lower gravity on Mars makes it easier to turn a blade or equivalent. There have been NASA-funded studies suggesting it is feasible. I think they use smaller maglev turbines or something like that.

The other aspect you've overlooked is my specific proposal to create topographical features (narrowing tunnels, mazes, canyons) that increase the gas density and thus wind force. Imagine a circular structure with tapering tunnels or passages, arranged like the spokes of wheel, with an all-directional turbine at the centre. From whichever direction the wind was coming the force would presumably be maximised at the centre.

Calliban wrote:

Louis, the lower gravity of Mars does not increase the kinetic energy in its winds. This is a function of wind speed and air density.
W = 0.5 x n x A x rho x v^3.
Let's say average winds peed of 7m/s and efficiency 40%, which is 80% of the Betz limit. Rho = 0.02kg/m3.
W= 0.5 x 0.4 x 1 x 0.02 x 7^3 = 1.37W/m2 of swept area.
A wind turbine with blade diameter 100m, would generate 10.8kW. Not a good net energy return I would suggest.

SpaceNut · 2021-04-24 06:40:09

Kbd512 ionic wind potential on mars is more probable as the dust makes the air have differences in charge such that the collection plates as the air passes change in energy state from the static that the air holds on mars.

Mars air while is has less force with the same wind speed we will see that on mars the speed of force is going to make use of that which we can not here on earth as we will be using light mass materials that are strong to tolerate the wind force difference with the prop designs. Yes channeling will aid in force wind speed concentration where possible to make energy efficiency windmill.

GW Johnson · 2021-04-24 09:49:31

"Secondly the gravity being 38% of Earth's, means the effective ability of the Mars wind to move a turbine is much higher all else being equal (which it isn't, granted). "

I agree with Calliban: gravity has nothing to do with how easy it is to move a wind turbine blade. That has to do with force acting on mass, and mass is unaffected by gravity. Doesn't matter which way the turbine axis is oriented, either.

As for "air density" on Mars, we are far enough from the critical point of CO2, and at ordinary-enough pressures and temperatures, to reliably use the ideal gas model P = rho R T. Use it in the form rho = P MW / Ru T, where Ru is the universal gas constant, and R = Ru / MW. On Mars, P = 6 mbar = 0.592% of a standard atmosphere. MW ~ 44.01. T varies, but about 0 F = -18 C would be sort of typical. At those conditions I get (using units more familiar to me) 7.760 x 10^-4 lbm/ft^3 = 1.014% of Earth sea level standard density. That's more than I thought it would be, but still quite small.

The higher molecular weight and the colder temperature offset the pressure ratio to get a somewhat higher density ratio, which is still quite low. While there is no "sea level" on Mars, there is an accepted datum elevation, at which the pressure is 6 to 7 mbar. At lower elevations, such as the bottom of Valles Marineris, it is nearer 10-12 mbar. Factor 2 increase in pressure, if at the same temperature, gets you a density ratio nearer 2% of standard, instead of 1% of standard. Twice nothing is still nothing.

The gravity has only to do with weight forces, no other forces. That would be for things like the soil bearing pressure exerted by massive objects, how big and powerful a crane you need to pick something up, how much friction a mass has moving across a surface, how much friction you can get from a stake or piling inserted into the ground, and stuff like that.

GW

Last edited by GW Johnson (2021-04-24 09:51:13)

SpaceNut · 2021-04-24 19:25:54

For mars like on earth we would be using a low rpm wind speed windmill turbine for the mars applications with modifications being made to the props shape and mass to allow more force to be captured by the wind on mars. On earth we translate speed to torque for the higher mass of gear drive generators for the large wind mills but on mars I think we should change to direct with a different coil arrangement.

https://www.greenhomegnome.com/wind-tur … nd-speeds/

The first thing you need to know is that wind power is proportional to the cube of wind speed, meaning that if a turbine generates 1 KW at 10 mph, that same turbine will generate 8 KW at 20 mph (double the wind speed3 = 2 x 2 x 2).

https://dbldkr.com/how-fast-do-wind-tur … they-look/

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Vertical Wind Turbine - better than you might think

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