Components of air liquefy at approximately 70 K. Assuming isentropic expansion from a reservoir in a supersonic facility:

a. Calculate the highest free-stream supersonic Mach number that the reservoir may be expanded to if the reservoir is at room temperature (22 degC).

b. Calculate the pressure and density in the free-stream of such a wind tunnel if the reservoir pressure is 3 bar.

c. Calculate the free-stream sound speed and velocity in the wind tunnel.

d. Calculate the Reynolds number in the free-stream per unit meter. Re/m = (rho U)/mu. Use Sutherland’s law to calculate the viscosity, mu, at the free-stream temperature. What is the Reynolds number for a plate that is 500 mm long? Will the boundary layer have transitioned to turbulent at the end of the plate?

e. Calculate the area ratio required to expand the gas to the Mach number in this wind tunnel. If the exit diameter must be 300 mm, what is the diameter of the throat?