Vortex shedding
Vortex shedding
(OP)
Hi all,
Do anybody know simply calculation of the effect of vortex shedding on structure? If I have a circular plate 10.0m dia. and wind blows right to it.
Thanks
OAP
Do anybody know simply calculation of the effect of vortex shedding on structure? If I have a circular plate 10.0m dia. and wind blows right to it.
Thanks
OAP






RE: Vortex shedding
RE: Vortex shedding
If you want so please post an e-mail address.
It is based in
Structural Dynamics in Practice
Arthur Bolton
Mc Graw Hill International
UK 1994
RE: Vortex shedding
RE: Vortex shedding
Often very large structures conduct additional wind studies to determine the flow characteristics of air flow from down draft and vortex sheading .
Cheers
RE: Vortex shedding
RE: Vortex shedding
Blacksmith
RE: Vortex shedding
You might also want to check out this Thread507-6585
Pals here did a good job there.
respects
IJR
RE: Vortex shedding
I also have software available for design of stack/chimneys, which includes checks for vortex shedding per ASME STS-1-2000 and CICIND 1999.
OAP - I will be happy to run your situation on my software if you want to give me the specifics (Ht, Dia, Thk, Mat'l, etc...)
Regards,
Chris
chris@mecaconsulting.com
www.mecaconsulting.com
RE: Vortex shedding
Actually, my structure is not a stack. It's a logo sign dia. of 10.0 m. which stand on the roof top of building. The level of the sign is about 210.0m from ground level. The thickness of sign is 0.30m and when included the supporting frame is to be 1.50m. There is a steel louvre wall behind of the sign 3.00m. away. This sign is fixed to a column at the mid of the sign. At top of a sign, I will provide the space truss which fixed to the toop of column to take the vertical & horizontal load fron the sign. At bottom of sign , I can provide the several plane trusses which fixed to preimeter beams to support the sign frame. The wind speed (returns periods 100 years) is about 29 m/s and I calculated the wind pressure at right angle to sign is 3 kN/sq.m.
By the way, due the behind of sign is empty, so I'm worried about the effect of Vortex shedding. If you guys have any further suggestion, it will be appreciate.
Thank again
OAP
RE: Vortex shedding
Your case? I guess the chance is that vortex shedding will be less a problem than unbalanced wind loads and suctions and gusts.
I suggest you design your support system for wind pressures and suctions given in codes(I know DIN 1055 part 4 for examp
le give you pressure coefficients accordingly). The empty(leeward) side will be subjected to suction and you may consider different combinations of pressure/suctions etc a bit conservatively
We carried out a similar design before for a roof structure using code coefficients, and worried about dynamics, we submitted our design for wind tunnel testing. Results did not differ much from those given in the codes.
good luck
IJR
RE: Vortex shedding
Russell Keays
RE: Vortex shedding
Your suggestion is very helpful for me. Furthermore, after I did the dynamic analysis in 3D, I got the first 3 mode frequency as follow:
1st mode = 16.05 Hz
2nd mode = 19.01 Hz
3rd mode = 19.7 Hz.
I think the dynamic problem will not be significant, right? Am I correct?
OAP