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dropdeadmarc
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Homework Statement
Theres a atmospheric tank with a goose neck vent on the top and also an inlet pipe [a diameter 2 inch schedule 40] on the top. There is a compressed air line [from a 50 psi compressor] going into the inlet. The pressure inside the tank should not be above 2 psi. Size the diameter of the goose neck vent.
Inlet:
P = 50 psi
Dinner = 2.07 inches
ρ = 4.32 lb/ft^3
Goose Neck Vent:
P = 2 psi
Dinner = ?
Homework Equations
Bernoulli's
0.5ρV2 + P = 0.5ρV2 + P
Q = V*A [volumetric flow rate]
V*A = V*A [in = out]
The Attempt at a Solution
I assumed I could use bernoullis to find the V out from the compressed air line. [Pinside = 50, Poutside = 0 [atmsophere], Vin = 0, Vout=?]
I got a Velocity of 68.31300511 ft/s
From that and the cross sectional area of the 2.07in pipe I got a Q of 95.79056195 CFM.
Next I moved onto the tank. I substituted
VinAin/Aout = Vout into Bernoulli's and Solved for Aout.
Aout = sqrt( Q2 / (Vin2 - 2*ΔP/ρ)
Problem is I ended up getting the same cross sectional area as the inlet. I'm not sure where I went wrong. Perhaps incompressible flow? I appreciate any help.