I WILL RATE IT AS LIFESAVER PLEASE HELP You have been asked to design an experim

Question

I WILL RATE IT AS LIFESAVER PLEASE HELP

You have been asked to design an experiment to measure aerodynamic forces on a building using a 1/80 scale replica of the prototype. It has been determined that the wind velocity on the prototype is 32 ft/s when the density of the air is 0.0024 slugs/ft3. You are using a wind tunnel with a maximum velocity of 320 ft/s. Because the temperatures are basically the same, the viscosity of the air for both the model and the tunnel can be considered the same. What air density would you need for the wind tunnel test for dynamic stability? While you are testing, you measure a 48 lbf force on the model. What will the force be on the prototype?

Explanation / Answer

Parameters:

Velocity u, Density D, volume V, Force F

Let us consider a PI term (non-dimensional) given by:

X = F/ru

where is the viscosity, r is the scale length

for the prototype and model X remains the same and also remains same

F1/(r1.u1) = F2/(r2.u2) where 1 denotes prototype and 2 denotes model

F1 = F2*(r1/r2)*(u1/u2) = 48*80*(32/320) = 48*8 = 384 lbf Ans

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