The drag characteristics for a newly designed automobile having a maximum characteristic length of 20 ft are to be determined through a model study. The characteristics at both low speed (approximately 20 mph) and high speed (90 mph) are of interest. For a series of projected model tests, an unpressurized wind tunnel that will accommodate a model with a maximum characteristic length of 4 ft is to be used. Determine the range of air velocities that would be required for the wind tunnel if Reynolds number similarity is desired. Are the velocities suitable

The speed range is between 100 and 450 mph (not possible)

Explanation:

Given data:

Maximum characteristic length = 20 ft

Low speed = 20 mph

High speed = 90 mph

Maximum characteristic length of the model = 4 ft

Question: Determine the range of air velocities that would be required for the wind, VMT = ?

Are the velocities suitable?

It is desired that Reynolds's number be equal

Re = (Re)MT

Here MT is model test

Substituting

Velocity at slow speed:

Velocity at high speed

The speed range is between 100 and 450 mph (not possible)

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