I went to a technical seminar a while ago sponsored by the local Niagara
area building officials where RWDI from Guelph made a presentation. It
included a video about simulated wind testing in a water tank with a
fine sand about the consistency of icing sugar. The flow of water
caused the sand to flow and drift and they were able to measure the
results. The tank was relatively small compared to wind tunnel.
Perhaps this is the basis for some of this CFD.
Gary
Kevin Below wrote:
> 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@bigpond.com
> <mailto:sch.tectonic@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@bigpond.com
>
> Adelaide
>
> South Australia
>
> ------------------------------------------------------------------------
>
> *From:* Kevin Below [mailto:kbofoz@gmail.com
> <mailto:kbofoz@gmail.com>]
> *Sent:* Thursday, 22 November 2007 14:33
>
> *To:* seaint@seaint.org <mailto:seaint@seaint.org>
> *Subject:* Re: Wind tower design
>
>
>
> Harold, what is CFD ?
>
> On Nov 21, 2007 12:01 PM, Harold Sprague <spraguehope@hotmail.com
> <mailto:spraguehope@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@gmail.com <mailto:kbofoz@gmail.com>
> To: seaint@seaint.org <mailto:seaint@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@hotmail.com
> <mailto:spraguehope@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@gmail.com <mailto:kbofoz@gmail.com>
> To: seaint@seaint.org <mailto:seaint@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!
> <http://www.windowslive.com/share.html?ocid=TXT_TAGLM_Wave2_sharelife_112007>
>
>
>
>
>
> ------------------------------------------------------------------------
>
> Share life as it happens with the new Windows Live. Share now!
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