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RE: Wind tower design

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Robert's caution should be seriously considered.  They don't use the super computers that often, but they daisy chain a bunch of computers for some serious heavy lifting.  I had one such problem which ran on a lot of daisy chained computers for several days on a CFD.  Even then, it is advised to verify the analysis with some real world testing. 

Regards,
Harold Sprague

> Date: Sat, 24 Nov 2007 17:08:01 -0800
> From: rkazanjy(--nospam--at)gmail.com
> 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=dateADALAd1&site=nasa_collection&ie=UTF-8&client=nasa_production&oe=UTF-8&proxystylesheet=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.
> >
> >
> >
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