Drag Coefficient
Drag Coefficient
(OP)
Does anyone know what the drag coefficient is for an aluminum flag pole? I am trying to do an analysis with a 90 mph wind speed.
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RE: Drag Coefficient
If you have access to "EIA/TIA-222-F or G" Standard, there are tables for drag coeff. for round and octagonal monopoles.
In Canada, S37-01 is followed instead of EIA/TIA standard and also has the same tables.
In NBCC-95 Commentary Fig. B-18 can be used to get the wind pressure without going thru calculation of drag coeff.
Hope this helps.
Lokstr
RE: Drag Coefficient
RE: Drag Coefficient
It is in Section 3.8.6 in the 2001 AASHTO code for signs, luminaires, and something else. They give equations for different shapes, but I didn't see anything about materials. I don't think it will matter, though.
RE: Drag Coefficient
RE: Drag Coefficient
Cfig = 0.05 + 0.7 * [mf / (ρair*c)] * (Aref / c2)-1.25
where
Cfig = aerodynamic shape factor (dimensionless)
mf = unit mass of flag (kilograms per square metre)
ρair = density of air (1.2 kilograms per cubic metre)
c = height of flag (metres)
lf = length of flag (metres)
Aref = area of flag (square metres)
for a rectangular flag, Aref = c * lf
for a pennant flag, Aref = 0.5 * c * lf
The design wind pressure is then:
p = 0.5 * ρair * Vdes2 * Cfig
where:
p = design wind pressure (pascals, 1 Pa ≅ 0.02 psf)
ρair = density of air (1.2 kilograms per cubic metre)
Vdes = design wind speed (metres per second)
Cfig = aerodynamic shape factor (dimensionless)
RE: Drag Coefficient
RE: Drag Coefficient
https://www.naamm.org/items.aspx
It's $25 and you also get another manual. You will need to know the size of the flag and what's it is made of.