Another maffs thing I don't unnerstand

User avatar
pErvinalia
On the good stuff
Posts: 59295
Joined: Tue Feb 23, 2010 11:08 pm
About me: Spelling 'were' 'where'
Location: dystopia
Contact:

Re: Another maffs thing I don't unnerstand

Post by pErvinalia » Fri Jun 15, 2018 11:24 pm

Rum wrote:
Fri Jun 15, 2018 9:04 pm
Brian Peacock wrote:
Fri Jun 15, 2018 8:52 pm
The effective area of a wind turbine is the circle described by the radius of it's blades.
  • Area of a circle = πr2
    10m radius: A = 314.16m2
    20m radius: A = 1256.64m2
The effective area of the 20m turbine is 1256.64/314.16 = 4 times greater than that of the 10m turbine.
Basic geometry from Form 3. Of course I knew that..but kind of forgot it...*cough* :mrgreen:
But that's not squaring the energy produced. That's just squaring the area of wind interception.
Sent from my penis using wankertalk.
"The Western world is fucking awesome because of mostly white men" - DaveDodo007.
"Socialized medicine is just exactly as morally defensible as gassing and cooking Jews" - Seth. Yes, he really did say that..
"Seth you are a boon to this community" - Cunt.
"I am seriously thinking of going on a spree killing" - Svartalf.

User avatar
Brian Peacock
Tipping cows since 1946
Posts: 37953
Joined: Thu Mar 05, 2009 11:44 am
About me: Ablate me:
Location: Location: Location:
Contact:

Re: Another maffs thing I don't unnerstand

Post by Brian Peacock » Sat Jun 16, 2018 12:32 am

See JimC's answer above.
Rationalia relies on voluntary donations. There is no obligation of course, but if you value this place and want to see it continue please consider making a small donation towards the forum's running costs.
Details on how to do that can be found here.

.

"It isn't necessary to imagine the world ending in fire or ice.
There are two other possibilities: one is paperwork, and the other is nostalgia."

Frank Zappa

"This is how humanity ends; bickering over the irrelevant."
Clinton Huxley » 21 Jun 2012 » 14:10:36 GMT
.

User avatar
pErvinalia
On the good stuff
Posts: 59295
Joined: Tue Feb 23, 2010 11:08 pm
About me: Spelling 'were' 'where'
Location: dystopia
Contact:

Re: Another maffs thing I don't unnerstand

Post by pErvinalia » Sat Jun 16, 2018 12:41 am

See my answer above that. That will only square the energy produced in a frictionless and weightless environment. I.e. doubling the length of turbine blades doesn't square the energy produced. :roll:
Sent from my penis using wankertalk.
"The Western world is fucking awesome because of mostly white men" - DaveDodo007.
"Socialized medicine is just exactly as morally defensible as gassing and cooking Jews" - Seth. Yes, he really did say that..
"Seth you are a boon to this community" - Cunt.
"I am seriously thinking of going on a spree killing" - Svartalf.

User avatar
pErvinalia
On the good stuff
Posts: 59295
Joined: Tue Feb 23, 2010 11:08 pm
About me: Spelling 'were' 'where'
Location: dystopia
Contact:

Re: Another maffs thing I don't unnerstand

Post by pErvinalia » Sat Jun 16, 2018 12:43 am

You know, you are becoming a real pain in the arse. And you know how I treat people like that. Is this really where you want to go?
Sent from my penis using wankertalk.
"The Western world is fucking awesome because of mostly white men" - DaveDodo007.
"Socialized medicine is just exactly as morally defensible as gassing and cooking Jews" - Seth. Yes, he really did say that..
"Seth you are a boon to this community" - Cunt.
"I am seriously thinking of going on a spree killing" - Svartalf.

User avatar
JimC
The sentimental bloke
Posts: 73014
Joined: Thu Feb 26, 2009 7:58 am
About me: To be serious about gin requires years of dedicated research.
Location: Melbourne, Australia
Contact:

Re: Another maffs thing I don't unnerstand

Post by JimC » Sat Jun 16, 2018 1:49 am

pErvinalia wrote:
Sat Jun 16, 2018 12:41 am
See my answer above that. That will only square the energy produced in a frictionless and weightless environment. I.e. doubling the length of turbine blades doesn't square the energy produced. :roll:
It will be a pretty good approximation, given that modern turbines have magnetic bearings with very little friction...

Another vital factor is the height of the swept area above ground - the higher the better, given the ground turbulence effect...
Nurse, where the fuck's my cardigan?
And my gin!

User avatar
pErvinalia
On the good stuff
Posts: 59295
Joined: Tue Feb 23, 2010 11:08 pm
About me: Spelling 'were' 'where'
Location: dystopia
Contact:

Re: Another maffs thing I don't unnerstand

Post by pErvinalia » Sat Jun 16, 2018 1:57 am

I'm sorry, but no. If this gave a good approximation in the real world, we'd have turbines hundreds of metres tall. We don't, because the gains become incremental due to losses from increasing weight and increasing friction. And friction isn't just in the bearings. It's also as the blade cuts through the air.
Sent from my penis using wankertalk.
"The Western world is fucking awesome because of mostly white men" - DaveDodo007.
"Socialized medicine is just exactly as morally defensible as gassing and cooking Jews" - Seth. Yes, he really did say that..
"Seth you are a boon to this community" - Cunt.
"I am seriously thinking of going on a spree killing" - Svartalf.

User avatar
JimC
The sentimental bloke
Posts: 73014
Joined: Thu Feb 26, 2009 7:58 am
About me: To be serious about gin requires years of dedicated research.
Location: Melbourne, Australia
Contact:

Re: Another maffs thing I don't unnerstand

Post by JimC » Sat Jun 16, 2018 4:03 am

pErvinalia wrote:
Sat Jun 16, 2018 1:57 am
I'm sorry, but no. If this gave a good approximation in the real world, we'd have turbines hundreds of metres tall. We don't, because the gains become incremental due to losses from increasing weight and increasing friction. And friction isn't just in the bearings. It's also as the blade cuts through the air.
Actually, we do have turbines that have a hub height of around 180 metres, and with the tip of the blades reaching to 250 metres. The fact that there will be limits on turbines beyond a certain size has nothing to do with a very clear and exact relationship between power and the square of blade length. There are several reasons why going much bigger than the biggest current turbines would not be sensible, but friction is not the issue (both air and magnetic bearing friction is small compared to the propulsive force of the air, and would increase only in a linear fashion in any case). The limitations on size are largely problems of strength, weight and rigidity, plus the engineering difficulties of manufacture and erecting such giants. You would reach a point where it is more economical to have 4 of the current giants rather than 1 super giant producing the same power as the 4.
Nurse, where the fuck's my cardigan?
And my gin!

User avatar
pErvinalia
On the good stuff
Posts: 59295
Joined: Tue Feb 23, 2010 11:08 pm
About me: Spelling 'were' 'where'
Location: dystopia
Contact:

Re: Another maffs thing I don't unnerstand

Post by pErvinalia » Sat Jun 16, 2018 4:29 am

The difficulties are what I and Svarty are talking about. So it's wrong to claim a wind turbine will output the square of its power when it doubles in prop length. A theoretical turbine would, but in the real world, no.
Sent from my penis using wankertalk.
"The Western world is fucking awesome because of mostly white men" - DaveDodo007.
"Socialized medicine is just exactly as morally defensible as gassing and cooking Jews" - Seth. Yes, he really did say that..
"Seth you are a boon to this community" - Cunt.
"I am seriously thinking of going on a spree killing" - Svartalf.

User avatar
JimC
The sentimental bloke
Posts: 73014
Joined: Thu Feb 26, 2009 7:58 am
About me: To be serious about gin requires years of dedicated research.
Location: Melbourne, Australia
Contact:

Re: Another maffs thing I don't unnerstand

Post by JimC » Sat Jun 16, 2018 5:06 am

pErvinalia wrote:
Sat Jun 16, 2018 4:29 am
The difficulties are what I and Svarty are talking about. So it's wrong to claim a wind turbine will output the square of its power when it doubles in prop length. A theoretical turbine would, but in the real world, no.
Well before those real-world difficulties emerge (when going beyond the current giants I mentioned), the relationship would in fact hold. A blade length of 4 metres would produce 4 times the power of a 2 metre blade.
Nurse, where the fuck's my cardigan?
And my gin!

User avatar
Rum
Absent Minded Processor
Posts: 37285
Joined: Wed Mar 11, 2009 9:25 pm
Location: South of the border..though not down Mexico way..
Contact:

Re: Another maffs thing I don't unnerstand

Post by Rum » Sat Jun 16, 2018 7:50 am

They said it in Youtube so it must be true. Plus Jim is a maffs god!

User avatar
Scot Dutchy
Posts: 19000
Joined: Tue Feb 23, 2010 2:07 pm
About me: Dijkbeschermer
Location: 's-Gravenhage, Nederland
Contact:

Re: Another maffs thing I don't unnerstand

Post by Scot Dutchy » Sat Jun 16, 2018 7:56 am

There is a thing called "moment" (the air speed needed to turn the blades). Different designs have different moments . The shape of the blade has a great influence on the moment. The ones with the smallest moment cant handle strong winds and have to be feathered to avoid damage. The ones with the biggest moment can handle very strong winds but need mechanical help to get moving.
The mount of power produced is not just dependent on size but on design.
"Wat is het een gezellig boel hier".

User avatar
Rum
Absent Minded Processor
Posts: 37285
Joined: Wed Mar 11, 2009 9:25 pm
Location: South of the border..though not down Mexico way..
Contact:

Re: Another maffs thing I don't unnerstand

Post by Rum » Sat Jun 16, 2018 8:04 am

I'm sure that is a factor but the OP was about the relationship between blade length and energy production and for me at any rate the odd thing that it is so proportional.

User avatar
Scot Dutchy
Posts: 19000
Joined: Tue Feb 23, 2010 2:07 pm
About me: Dijkbeschermer
Location: 's-Gravenhage, Nederland
Contact:

Re: Another maffs thing I don't unnerstand

Post by Scot Dutchy » Sat Jun 16, 2018 8:12 am

Rum wrote:
Sat Jun 16, 2018 8:04 am
I'm sure that is a factor but the OP was about the relationship between blade length and energy production and for me at any rate the odd thing that it is so proportional.
Blade length is not the story but design is.

Wind Turbine Blade Design, Flat or Curved

Wind turbine design: Building a better blade
"Wat is het een gezellig boel hier".

User avatar
Rum
Absent Minded Processor
Posts: 37285
Joined: Wed Mar 11, 2009 9:25 pm
Location: South of the border..though not down Mexico way..
Contact:

Re: Another maffs thing I don't unnerstand

Post by Rum » Sat Jun 16, 2018 8:37 am

Scot Dutchy wrote:
Sat Jun 16, 2018 8:12 am
Rum wrote:
Sat Jun 16, 2018 8:04 am
I'm sure that is a factor but the OP was about the relationship between blade length and energy production and for me at any rate the odd thing that it is so proportional.
Blade length is not the story but design is.

Wind Turbine Blade Design, Flat or Curved

Wind turbine design: Building a better blade
No. The story is blade length. That is what the OP says.

User avatar
Scot Dutchy
Posts: 19000
Joined: Tue Feb 23, 2010 2:07 pm
About me: Dijkbeschermer
Location: 's-Gravenhage, Nederland
Contact:

Re: Another maffs thing I don't unnerstand

Post by Scot Dutchy » Sat Jun 16, 2018 8:43 am

Nope design or cant you see that. What sort of blade? Shape and thickness is far more important. No blade is a simple blade.
"Wat is het een gezellig boel hier".

Post Reply

Who is online

Users browsing this forum: No registered users and 22 guests