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RE: Wind tower design

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Bob 
Robert Kazanjy wrote:

I would depend on a wind tunnel modeling expert and someone with
expensive cfd experience and aerodynamic flutter experience.

Was that meant to be extensive experience?
Or intentional that it's expensive?


Regards
Conrad Harrison
B.Tech (mfg & mech), MIIE, gradTIEAust
mailto:sch.tectonic(--nospam--at)bigpond.com
Adelaide
South Australia
-----Original Message-----
From: Robert Kazanjy [mailto:rkazanjy(--nospam--at)gmail.com] 
Sent: Sunday, 25 November 2007 11:38
To: seaint(--nospam--at)seaint.org
Subject: Re: Wind tower design

CFD has been around since at least the mid 70's.

My first exposure to is was during a tour (Spring '75) of NASA Ames
Research Center at Moffett Field, CA

They were (at the time) doing some pretty advanced stuff, flow over
the space shuttle during re-entry.
 At the time the computational demands were at the very limits of
super-computing capability (think Cray).

http://www.nasa.gov/centers/ames/home/index.html

http://search.nasa.gov/search/search?q=cfd&output=xml_no_dtd&sort=dateADALAd
1&site=nasa_collection&ie=UTF-8&client=nasa_production&oe=UTF-8&proxystylesh
eet=nasa_production


cfd has come a long way in the last 30 years, don't need super
computers to do the more "mainstream" stuff.

but like with any sophisticated analytical tool (like FEM), in the
hands of the inexperienced, the results could be questionable.


I would depend on a wind tunnel modeling expert and someone with
expensive cfd experience and aerodynamic flutter experience.


cheers
Bob




On Nov 24, 2007 11:51 AM, Harold Sprague <spraguehope(--nospam--at)hotmail.com> wrote:
>
>  Computational Fluid Dynamics.  There are several programs that can do
this
> kind of work.
>
> Regards,
> Harold Sprague
>
>
>  ________________________________
>  Date: Wed, 21 Nov 2007 23:03:07 -0500
>
>
> From: kbofoz(--nospam--at)gmail.com
> 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
>
> From: kbofoz(--nospam--at)gmail.com
> To: seaint(--nospam--at)seaint.org
>
> 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.
>
>
>
>  ________________________________
>  Share life as it happens with the new Windows Live. Share now!
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