Question

you are given a 1/5 model of a car that normally runs at 30 mph. what wind tunnel speed should you use to test the car? (assume kinematic viscosity does not change and )

Answer 1

The wind tunnel speed that must be used to test the car 1 / 5 model of a car that normally runs at 30 mph is 150 mph

Re = u L / ν

Re = Reynold's number

u = Flow speed

L = Characteristic linear dimension

ν = Kinematic viscosity

ν$_{p}$ = 1.516 * $10^{-5}$ m² / s

ν$_{p}$ = ν$_{m}$ = 1.516 * $10^{-5}$ m² / s

L$_{m}$ = L$_{p}$ / 5

u$_{p}$ = 30 mph

Re$_{m}$ = u$_{m}$ L$_{p}$ / 5 * 1.516 * $10^{-5}$

Re$_{p}$ = 30 L$_{p}$ / 1.516 * $10^{-5}$

In tunnel,

Re$_{m}$ = Re$_{p}$

u$_{m}$ L$_{p}$ / 5 * 1.516 * $10^{-5}$ = 30 L$_{p}$ / 5 * 1.516 * $10^{-5}$

u$_{m}$ = 30 * 5

u$_{m}$ = 150 mph

Therefore, the wind tunnel speed that must be used to test the car is 150 mph

To know more about Reynold's number

brainly.com/question/12977616

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