Question

A large tank supplies air to a converging nozzle that discharges to atmospheric pressure. Assume the flow is reversible and adiabatic. For what range of tank pressures will the flow at the nozzle exit be sonic? If the tank pressure is 600 kPa (abs) and the temperature is 600 K, determine the mass flow rate through the nozzle, if the exit area is 0.00129 m².

Answer 1

To have sonic flow at an converging orifice, the head (tank) pressure must be (k + 1)/2]^(k/(k-1)) times atmospheric pressure. "k" is the specific heat ratio. For air with k = 1.4 , that ratio is 1.893

For more details, see
http://en.wikipedia.org/wiki/Choked_flow