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Re: Wind tower design

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So CFD is a method which can be used to simulate air flow around objects, and come up with wind pressures ?  I had never heard of it.


On Nov 21, 2007 11:17 PM, Conrad Harrison < sch.tectonic(--nospam--at)bigpond.com> wrote:

Being as I'm here!

 

CFD =computational fluid dynamics

 

And from recent articles I have read, it is still early days regarding wind loading, and can take hours to days for the computer to crunch the numbers. It still largely a research tool with few practical programs available.

 

It is also used for research into fire behaviour.

 

Regards

Conrad Harrison

B.Tech (mfg & mech), MIIE, gradTIEAust

mailto:sch.tectonic(--nospam--at)bigpond.com

Adelaide

South Australia


From: Kevin Below [mailto:kbofoz(--nospam--at)gmail.com]
Sent: Thursday, 22 November 2007 14:33


To: seaint(--nospam--at)seaint.org
Subject: Re: Wind tower design

 

Harold, what is CFD ?

On Nov 21, 2007 12:01 PM, Harold Sprague <spraguehope(--nospam--at)hotmail.com> wrote:

Don't write off circular shapes.  The circular shape may be the most structurally efficient and most effective for construction.  It generally is when it comes to stacks in spite of the vortex shedding problem. 
 
Stacks have the same tendency of vortex shedding.  It is mitigated by strakes or active damping.  The blades themselves of a wind power generator may mitigate the forming of the vortices. 
 
Regardless, my limited experience with high end computer modeling is that a lot of the CFD codes will give you any answer you want.  What you need are data points that verify the CFD model.  I would suggest you speak with Jon Peterka at CPP in Ft. Collins.  He knows modeling and he knows the limitations of CFD modeling.  He may have already modeled this. 

Regards,
Harold Sprague


Date: Mon, 19 Nov 2007 12:53:55 -0500

Subject: Re: Wind tower design

Thanks for the feedback Harold,
I am looking at the probability of wind tunnel testing, as well as theoretical studies to determine the dynamic properties. 
I will be asking the wind experts about vortex shedding.  I will probably be using a non-circular cross-section to reduce the vortex shedding, but I don't yet know if a hexagonal or pentagonal shape is better than circular.  I believe the best would be pentagonal, but that will be a discussion with the wind tunnel people.

Kevin

On Nov 19, 2007 12:17 PM, Harold Sprague <spraguehope(--nospam--at)hotmail.com> wrote:

I doubt that you will find any sort of code or design guide on this topic.  I would suggest that a wind tunnel study be conducted especially if this is for operational wind load characteristics.  If this is for extreme wind effects, I would think that the dominate issue will be the vortex shedding on the mast. 

Regards,
Harold Sprague


Date: Fri, 16 Nov 2007 22:02:19 -0500
From: kbofoz(--nospam--at)gmail.com
To: seaint(--nospam--at)seaint.org
Subject: Wind tower design



Has anybody done any wind tower design work ?  I am doing some preliminary work on a concrete tower design, and I am thinking about the dynamic behaviour
and the effect of the passage of the blade when it passes in front of the tower.  Does anyone have any information or ideas on this ?

The Germans and the Japanese have actually built some concrete towers already.  Apparently steel towers are at about their height limit now, and the way to greater efficiency and bigger turbines leads to higher towers, which will probably be in concrete.

 


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