Posted by Katie on .
A convergingdiverging nozzle with a throat area of 2 in² is connected to a large tank in which air is kept at a pressure of 80 psia and a temperature and a temperature of 60°F. If the nozzle is to operate at design conditions (flow is isentropic) and the ambient pressure outside the nozzle is 12.9 psia, calculate the ext area of the nozzle and the mass flow rate.

Fluid Mechanics 
drwls,
Use isentropic flow tables for supersonic flow (with k = 1.4) to achieve a pressure reduction factor of P/Po = 12.9/80 = 0.16125
You should get a Mach number of 1.85 and a flow area ratio A/A* = 1.495
The exit area should be 1.495 times the throat area, or 3.0 square inches.
The inside temperature is not needed.