Talk:Wind turbine design

Energy Unassessed

	Energy portal This article is within the scope of WikiProject Energy, a collaborative effort to improve the coverage of Energy on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.EnergyWikipedia:WikiProject EnergyTemplate:WikiProject Energyenergy
???	This article has not yet received a rating on Wikipedia's content assessment scale.
???	This article has not yet received a rating on the project's importance scale.

Level of detail of each section

Does anyone else think that this page attempts to cover too many topics? I have noticed that the aerodynamics section contains a link to an article which explains the aerodynamics of wind turbines much better. However, the same cannot be said of other sections such as power control, generators, including connection to the electric grid, etc. Surely some of these pages are worthy of pages in their own right no?

Smilesgiles89 (talk) 17:26, 17 April 2013 (UTC)[reply]

Connection to the electric grid

The article does not make any mention of the dangers of employing a DFIG topology. For one, a DFIG draws reactive power from the grid. In light of this, a DFIG wind turbin can contribute to instability in a transmission system. — Preceding unsigned comment added by Smilesgiles89 (talk • contribs) 17:19, 17 April 2013 (UTC) Smilesgiles89 (talk) 17:26, 17 April 2013 (UTC)[reply]

Vortex Generators

Vortex generators and micro-tabs should not be confused. I replaced the microtab references with vortex generators in the "Stall" section of the article. Micro tabs are serrated gurney flaps and not vortex generators. georgepehli (talk) 09:52, 10 February 2010 (UTC)[reply]

Stall section needs major re-writing!

I believe that the stall description is very poor and generally inaccurate. Sections like this one:

Stalling is simple because it can be made to happen passively (it increases automatically when the winds speed up), but it increases the cross-section of the blade face-on to the wind, and thus the ordinary drag

should be explained better and in a more accurate way.

Also, what vortex generators do, is that they induce vorticity to the boundary layer thus improving the BL mixing and eventually allow the BL to "stick" to the wall (i.e. airfoil or wind turbine blade) withstanding more adverse pressure gradients. The whole statement:

Vortex generators may be used to control the lift characteristics of the blade. The VGs are placed on the airfoil to enhance the lift if they are placed on the lower (flatter) surface or limit the maximum lift if placed on the upper (higher camber) surface

is completely wrong. First of all these is no "flat" airfoil surface, the terminology is Pressure Side and Suction Side. Then, the installation of VGs on the Pressure Side does NOT increase lift. What usually happens is that trip-stripes (i.e. zig zag tapes) are installed around mid-chord at the Pressure Side in order to fix the Laminar-Turbulent transition location and allow the tripped (i.e. turbulent) boundary layer to attach to the rear part of the pressure side of the airfoil. If this part is cambered (i.e. S shaped trailing edge) then the fact that the BL is attached will lead to a lift increase due to the trailing edge camber.

Regarding the suction side I do not see how the VGs would "limit the maximum lift". What they would do is generally control the stall and the post-stall behavior of the airfoil.

Finally the citation provided by the author of that part does NOT state any of the above (false) statements. georgepehli (talk) 09:52, 10 February 2010 (UTC)[reply]

Blade Materials Possible Fallacy

In the section on blade materials there is a piece which states : "One of the most important goals when designing larger blade systems is to keep blade weight under control. Since gravity scales as the cube of the turbine radius, loading due to gravity becomes a constraining design factor for systems with larger blades.[5]"

Firstly, I do not think the term "gravity" is correct here. Gravity will not increase or decrease significantly depending on how big wind turbine blades are, it's weight may, yes but it's gravity.... I don't think so. Also, there is mention that it will increase with the cube of the radius however the source cited does not confirm or deny this. —Preceding unsigned comment added by Brokengun (talk • contribs) 01:33, 21 December 2009 (UTC)[reply]

Can the dynamic braking resistor described in this article be at least partly replaced with ultracapacitors? That sounds like it could keep the energy from being wasted as heat and instead captured and trickled off slowly, still providing the needed braking and giving a boost to the turbine's efficiency and output. Only when the capacitors were topped out (and a great deal of capacitance could be used if wanted) would a resistor be used. Or am I misunderstanding how this works and this is not technically possible?

Wind turbine economics

"Due to the energy required to manufacture, transport, and erect the components of wind turbines it is debated if over the life of the turbine this energy will be recaptured.

Also utility companies rely on government subsidies to offset the cost of building wind farms which are two to three times the cost of equivalent capacity produced by coal fired units. After the subsidies run out the wind facility is normally sold to another utlity who begins to draw the subsidies once more."

These assertions don't seem to be relevant, supported or even referenced further within the article - what utility companies? what government? How does this relate to the topic of wind turbine design? Donquixote2u (talk) 02:08, 13 September 2009 (UTC)[reply]

Error in Indiana data

Part of the current article says "Indiana had been rated as having a wind capacity of 30 MW, but by raising the expected turbine height from 50 m to 70 m, the wind capacity estimate was raised to 40,000 MW, and could be double that at 100 m.[6]". The citation does indeed say this but I have to assume that something is wrong here. Obviously, raising the turbine height from 50m to 70m can't give a 1000 fold increase in power. The 30MW figure might be the states current output capacity (although NRELs 2007 report doesn't even provide a figure for Indiana). The 40,000 MW figure might represent a theoretical maximum output capacity but the citation doesn't provide a link to the actual NREL data. Either way, it is at best very confusing and at worst completely wrong.

Emphasis on larger wind turbines

Looking through the article it seems to only include the megawatt class turbines and not anything about kilowatt or even watt class turbines. Could someone try putting in more material on smaller turbines? Aicchalmers 14:46, 2 September 2007 (UTC)[reply]

Durability

The "Materials" section of the article briefly discusses materials used for modern wind turbine blades. However the durability (in years) or needed maintenance of the blades, the (steel) tower, or the internal parts is not discussed, but this information would be most welcome. (Any evaluation or cited experiences of the durability/maintenance would be turbine-type specific, so in my understanding this page would be the right place, instead of the more general "Wind turbine" page.) (85.156.172.166 (talk) 20:30, 7 March 2008 (UTC))[reply]

Rotation control

"High efficiency 3-blade-turbines have tip speed/wind speed ratios of 6 to 7" is ambiguous: does the ratio range from 6.0 to 7.0 or is it 6/7? —Preceding unsigned comment added by 71.205.58.127 (talk) 04:24, 4 July 2008 (UTC)[reply]

I assume it means between 6:1 and 7:1. Rocketmagnet (talk) 22:32, 19 May 2009 (UTC)[reply]

A dumb question (or two)

This keeps coming up on the Science Refdesk, so I'm going to try to figure it out.

If a three-blade turbine is good, why isn't a six-blade turbine twice as good? Is the only point of a wind turbine to turn the generator at a certain speed? Doesn't the electrical load on the turbine slow the blades down? If that was the case, one would think that twice as many blades would push the electrons through twice as hard (as it were), i.e. you could put twice the load on the generator.

I'm sure I'm missing something here, but it's not completely clear from reading the article so I appreciate any explanation. Thanks! Franamax (talk) 06:15, 22 July 2008 (UTC)[reply]

Your first question is in Wind_turbine_design#Blade_count "Increasing the number of blades from one to two yields a six percent increase in aerodynamic efficiency, whereas increasing the blade count from two to three yields only an additional three percent in efficiency. Further increasing the blade count yields minimal improvements in aerodynamic efficiency and sacrifices too much in blade stiffness as the blades become thinner." Mion (talk) 06:29, 22 July 2008 (UTC)[reply]

Yes, that's where my dumb questions multiply.

What does that mean, a six percent increase in aerodynamic efficiency - 6% of what? Where is "aerodynamic efficiency" defined?
And more, sacrifices too much in blade stiffness as the blades become thinner - I told you to add more blades, I never asked you to make them thinner. What happens when they stay thick?
And what does thick/thin refer to - length of the blade (trailing not radial)? profile presented to the wind? aerodynamic thickness of the blade itself?

Thanks for the quick response so far! Franamax (talk) 12:46, 22 July 2008 (UTC)[reply]

here Drag (physics) you improve the aerodynamic efficiency by lessening the friction forces (mostly), and looking at your other question, this was my last answer on this page. Cheers Mion (talk) 13:01, 22 July 2008 (UTC)[reply]

OK, so where do the friction forces lessen? Does that mean there is better balance on the central bearings?

And I'm not sure what you mean by my last answer on this page - an archived answer? Franamax (talk) 13:10, 22 July 2008 (UTC)[reply]

"I told you to add" , i'm not your dog, so please mind your language. Mion (talk) 13:20, 22 July 2008 (UTC)[reply]

Ohh, finally I get it - you're taking things personally. No, that was a figure of speech, a rhetorical formulation or what have you. Not a personal comment to you, not at all. The comments were actually directed to the disembodied voice of the article text (and if you wrote that text, then sorry again I guess :), asking the article to make itself more clear. I apologize for any misunderstanding, I'll plead the fact it took me this long to figure it out as evidence of my sincerity. Sorry :)

I try to approach technical questions directly, it's often the best way to get direct answers. Hopefully someone will tackle the questions because it's just not clear to me. Thanks. Franamax (talk) 19:13, 22 July 2008 (UTC)[reply]

he, no hard feelings, Cheers Mion (talk) 20:07, 22 July 2008 (UTC)[reply]

I must agree that I don't feel that this article has answered the question fully: Why not have 6 blades? Indeed, small turbines seem to have more blades. Also, the bit about aerodynamic efficiency could be explained a little better I think. What exactly is the input power in this case? Thanks Rocketmagnet (talk) 22:38, 19 May 2009 (UTC)[reply]

The 3rd paragraph in the Blade Count section especially needs more clarification. Quantalume Wanderer (talk) 04:26, 5 January 2010 (UTC)[reply]

Reference on the increased aerodynamic efficiency

It would be a good idea to have a reference for the increase in the aerodynamical efficincy of the wind turbine with the increasing number of blades —Preceding unsigned comment added by 193.190.163.52 (talk) 09:29, 19 August 2008 (UTC)[reply]

I definitely agree, as far as I am concerned those numbers are made up CombatWombat42 (talk) 15:42, 8 April 2013 (UTC)[reply]

It seems to be a popular opinion among those who write about aerodynamics; I put the first ref I found into the article. --Wtshymanski (talk) 16:37, 8 April 2013 (UTC)[reply]

How is the electricity from the head mounted Generator transmitted to the tower as the head yaws?

Surely if it was hard wired the wires would tangle? Some sort of slip ring to allow the transfer of power must exist, but not mentioned in the article. How about transferring the rotation of the power shaft through a crown gear - ie rotate 90 so as to be inline with the tower. then mount the genny on the tower vertically, and wire it up? —Preceding unsigned comment added by 82.30.126.139 (talk) 13:56, 24 February 2009 (UTC)[reply]

When the turbine controller detects that the power cables have been twisted by three rotations, it shuts the machine down and untwists them. --24.65.122.222 (talk) 02:50, 2 March 2009 (UTC)Wally Flint[reply]

The generator section is unclear

The generator explanation changes back and forth from asynchronous to synchronous machines and merges explanations from several different technologies. We should clearly define the different methods. —Preceding unsigned comment added by 74.98.33.199 (talk) 20:50, 13 June 2009 (UTC)[reply]

Induction Generator

This is NOT correct:

"Older style wind generators rotate at a constant speed, to match power line frequency, which allowed the use of less costly induction generators."

As odd as this might seem, a Tesla motor/generator (so-called squirrel cage rotor) does not need to run at a constant speed. It does need to run at a narrow speed range to function as a generator. It has a synchronous speed (ω) which is a function of the AC frequency (f) and the number of poles (n): ω = 120f/n. When used as a motor, it runs at less than that speed. The difference is usually called slip. As slip increases, the motor will produce more and more torque till the maximum is reached. If connected to a load, the motor will then stall. When used as a generator, it must be driven at a speed greater than the synchronous speed. As with use as a motor (but in reverse), the power produced increases as the slip increases until it reaches a peak. If that slip rate is exceed, the generator will produce less power. If slip continues to increase, a point will be reached where no power is produced and if that slip is exceeded, it will start absorbing power from the grid.

Tyrerj (talk) 22:38, 31 July 2010 (UTC)[reply]

Image

Can someone take over the picture at http://express.howstuffworks.com/gif/wind-power-horizontal.gif for the construction and design section ? Upload at wikimedia commons and show image here —Preceding unsigned comment added by 91.176.215.15 (talk) 10:49, 12 September 2009 (UTC)[reply]

No, because it is copyrighted, and belongs to the website... - Adolphus79 (talk) 13:08, 12 September 2009 (UTC)[reply]

I already took over the image myself, legally. Perhaps that the EERE_Illust_large_image may be imbedded to the image; the image I draw thus being the larger whole, and the with the EERE image as magnification of the head of the turbine (as it contains more info). The large picture has added info as it mentions the nacelle, rotor blades, rotor hub and transformer. See

91.182.191.178 (talk) 17:04, 12 September 2009 (UTC)[reply]

Image 2

Added this image, needs CGI'ing dough

Blade Shape

My 81-yr old mom asks a very elementary and important question, "What was wrong with the 4-arm dutch windmills of the 1800's ?? Why do modern wind turbines have such a different shape?" We should try to address this question early in the subsection about blade shape.

Also, from a cursory reading of the article, I cannot figure out what are the primary, secondary, and tertiary design criteria for a windmill blade design. Thus, this article fails to address a fundamental question about turbine design. For example, what's more important to efficient power generation, torque (which probably implies large blades), blade speed (which probably implies small blades), or availability (which probably implies lowering the stall windspeed, and thus blade mass and generator resistance and having variable pitch, so the turbine can generate power all the time)? SystemBuilder (talk) 18:55, 27 February 2010 (UTC)[reply]

Qn: mathematical analysis of the cyclic stresses in the blade root while rotating

Dear All,

When wind turbine rotor rotates it's blades especially blade roots undergo cyclic stresses. These stresses are due to gravitation forces and inertial forces.

Could any body of you explain me how these cyclic forces vary? I am interested to know the basic mechanics of these forces for example what would be the stress level in a blade root when the blade is perpendicular to group (pointing towards ground or sky), or the stress level when a blade is horizontal etc....(I am not much interested in Aerodynamics forces, since for steady mean wind flow they are constant)

Apart from basic mechanics of these stresses I would also like to go in the details of mathematical analysis of this phenomenon. So could you please suggest me some good reference book, lecture notes or any other written material.

thanks a lot in advance,

regards, Milind. —Preceding unsigned comment added by Milindashokshende (talk • contribs) 14:08, 26 May 2010 (UTC) This is terrible. This has nothing to do with wind turbines.[reply]

A turbine, by definition, is an exchange of momentum device. This whole article is about devices that operate on Bernoulli's Principle - not exchange of momentum.

This article is about "Wind Thingys." Because no one has come up with a neat sounding name for a device that operates on Bernoulli's principle is no excuse to gloom on to the word turbine.

This is improper

Ecarecar (talk) 20:36, 30 July 2011 (UTC)[reply]

ARTICLE has focus challenge per title

The title would invite consideration of design of any type of wind turbine, not just the towered HAWT. VAWT and other types ...belt, airborne are neglected. So, the sentence :"This article covers the design of horizontal axis wind turbines (HAWT) since the majority of commercial turbines use this design" is POV on "commercial" and does not count well, as VAWT and other sorts have a count that might be more than the count of the HAWTs.

WP:Notability and WP:SPLIT applies here. This article already has a reasonable size, and additions about VAWT, small or non-commercial types could be mentioned here but is best expanded upon in the relevant articles Unconventional wind turbines, Vertical axis wind turbine, Darrieus wind turbine, Savonius wind turbine, Small wind turbine and the like. The vast majority of wind energy production is made from large grid connected commercial HAWTs (as per [1] and maybe [2] ), they happen to be commercial because that is what is feasible. As for a non-commercial wind turbine, see [3] free to copy I guess, but so far feasibility seem to overwhelmingly prefer commercial solutions. TGCP (talk) 13:18, 18 December 2010 (UTC)[reply]

Wind Turbine Noise

I would question the statement in the current version (May 9) that the noise varies with the 5th power of the tip speed. If that were true the Vestas V47 (229 fps at nominal rotational speed) would be noisier than the Vestas V82 (202 fps at nominal rotational speed). There seems to be broad agreement that the reverse is true. —Preceding unsigned comment added by Carlfoss (talk • contribs) 22:43, 9 May 2011 (UTC)[reply]

Why are wide blades good for fans, but not wind turbines?

If your average house fan has wide fan blades that are designed to *efficiently move air*, then why won't that same basic blade design also be *efficiently moved by air* when applied to a wind turbine?

How can you extract the majority of energy in a circular field of wind by having narrow blades that occupy only a small fraction of that swept-area circular field?

Do water turbines have blades that only expose themselves to 10% or so of the total circular area of water rushing down a penstock water pipe? — Preceding unsigned comment added by 64.231.94.216 (talk) 21:46, 20 July 2011 (UTC)[reply]

I still don't know the answer to this one and I've been intermittently looking for it for some time. The fluid dynamics explanations I've read so far talk about the significance of the "chord" (the width of the blades), but I haven't found an explanation I understand well enough to paraphrase here. --Wtshymanski (talk) 01:13, 6 September 2011 (UTC)[reply]

It comes down to aerodynamics. "The total blade area as a fraction of the total swept disc area is called the solidity, and aerodynamically there is an optimum solidity for a given tip speed; the higher the number of blades, the narrower each one must be. In practice the optimum solidity is low (only a few percent) which means that even with only three blades, each one must be very narrow."[4] I found the comments here enlightening too. --Avenue (talk) 04:38, 6 September 2011 (UTC)[reply]

I suppose what the original question was asking and what I don't yet understand either is why the optimums seem to be different for fans vs. turbines; now, a household fan operates in a vastly different way than a wind turbine, but it would be good to have some comprehension as to why the answers are different for fan blades and turbine blades. Though I suspect no household fan blade has ever been optimized for aerodynamic performance! --Wtshymanski (talk) 14:12, 6 September 2011 (UTC)[reply]

Yes, I gather most household fans are too compact and slow (for good reasons) to be aerodynamically optimal. Ceiling fans might be the most similar to wind turbines. Efficiency can be more critical for industrial fans, but a wide range of designs are used there, and I don't know what they're all good for. ---Avenue (talk) 16:27, 6 September 2011 (UTC)[reply]

Aspect ratio (wing) (length/Chord) is important for lift-to-drag ratio; sailplanes are the most efficient. Blade design could elaborate on this. Power direction also means something, as much more wind speed (and power per area) can be transmitted from Propeller (aircraft) to air than from air to rotor, affecting tip speed and therefore aspect ratio. Fan thrust depends on blade area, but inline references for this is not found in the propeller article. TGCP (talk) 19:47, 30 April 2012 (UTC)[reply]

Constant speed turbines

Does anyone know how the turbines work which rotate at a constant speed irrespective of the wind speed? See for example this one http://www.endurancewindpower.com/wp-content/uploads/2010/08/E-3120-Product-Brochure-NA-20-Feb-2012-Webready.pdf which rotates at a constant 42 rpm. If they do, it would be worth adding to the article Drkirkby (talk) 04:09, 11 March 2012 (UTC)[reply]

That would be true of machines with synchronous or induction generators; they regulate power into the grid just like a hydro turbine running at fixed speed, by adjusting their blade pitch angle to maintain the speed constant. If we don't explain this in the article, we should. --Wtshymanski (talk) 18:02, 11 March 2012 (UTC)[reply]

Net energy production

Obviously, there is some consumption of electrical energy by the electronics, lights, orientation motors, hydraulic pumps (if fitted) etc. I presume the figures quoted for capacity or electricity generated are gross values. What is the average consumption of, say, a 2 MW turbine? Where I live, I have a clear view of part of a 6x1.8 MW farm, with apparently some form of synchronous generator, as the rotational speed is constant, no matter the wind speed. What intrigues me is that they often rotate with zero wind speed which suggests to me that either the generator acts as a motor or there must be a small motor to keep it turning in synchronism. I presume that the reason for this that the energy consumed in idling must be less than the energy needed to overcome the inertia of starting the blades from a standstill to working speed when the wind re-starts, so that if the average windspeed reaches the generation threshold of ~3.5 m/s, it can start producing immediately rather than wait until the blades reach synchronisation speed. This must consume quite some energy from the grid and this is never mentioned in the production figures. I feel that the article should contain some mention of wind turbine consumption. Unfortunately I do not feel competent to edit it myself. Devilinhell (talk) 15:26, 26 April 2012 (UTC)[reply]

I doubt that any turbine has a powered rotor - most likely it is a simple case of the Wind profile power law, where wind can feel still on ground but sufficient at hub height to move the blades, if not produce power. Some power is used for electronics and heating. TGCP (talk) 18:59, 30 April 2012 (UTC)[reply]

Thanks for your view. I did a quick search and indeed found a reference to motoring, albeit with a smaller turbine: "Motoring starts the blades spinning so the turbine operates in lighter wind conditions than if it relied solely on the wind to start." at http://www.endurancewindpower.co.uk/wp-content/uploads/2010/08/E-3120-Product-Brochure-UK-29-Aug-2011.pdf - there could be other references but I didn't have the time to seek them. I have made a deep study of the meteorological conditions in this region and roughly half the days (outside a few winter gale periods), my anemometer (at 22 m above ground level and approximately at hub level of the nearest turbine which is on lower ground) registers average daily wind speeds of <1 m/s. It often registers 0 m/s for hours on end in still anticyclonic conditions with isobar maps showing zero pressure gradient, yet the blades still turn. The Wind profile power law would not indicate that 0 m/s at ground level would give 3.5 m/s at 70 m. Unfortunately, the owners of the farm are not open to discussion, hiding behind what I feel must be a loss-making venture. I cannot obtain figures for the individual farm but I do obtain country-wide wind generation figures and the overall load factor for wind generation is typically, per month, 10-14%. For April:

Energy from wind MWh: 12231

Total energy, all sources MWh: 305321

Average power, wind, MW: 17.0

Average power, all sources, MW: 424.1

Wind capacity, MW: 133

Percentage wind power/wind capacity: 12.8% (load factor)

Percentage wind power/total power: 4.0%

Devilinhell (talk) 09:15, 3 May 2012 (UTC)[reply]

The anemometer on the turbine should be easily visible, and any wind that can move a 1 foot tri-cup should also move a 120-foot tri-blade. Whatever the case, we still need WP:Reliable sources to state the direction of power. TGCP (talk) 17:06, 3 May 2012 (UTC)[reply]

Gearless wind turbine

The section about Gearless wind turbines says "Gearless wind turbine are often heavier than gear based wind turbines." While this is true it might be good to mention that due to the missing gearbox a gearless wind mill is both lighter and require a smaller nacelle. — Preceding unsigned comment added by 109.228.168.107 (talk) 22:04, 15 October 2012 (UTC)[reply]

(Please put the new section on a talk page at the END of a talk page.)

Some gearless are lighter and smaller (SWP), some are heavier and larger (Enercon) than gearbox turbines. In both cases, we need references to support those claims. TGCP (talk) 18:57, 16 October 2012 (UTC)[reply]

Suggest merge

Design feasibilIty of Wind turbine systems is not about its title topic, but is about this topic. Any non-redundant useful content should be merged here. --Wtshymanski (talk) 20:37, 9 October 2013 (UTC)[reply]