Question

Which of this conditions is necessary to achieve flow in a nozzle?

(a) \(\frac {P_e}{P_0}\) < 1

(b) \(\frac {P_e}{P_0}\) > 1

(c) \(\frac {P_e}{P_0}\) = 1

(d) \(\frac {P_e}{P_0}\) = 0

The question was asked in an interview for internship.

I need to ask this question from Nozzles topic in division Quasi-One-Dimensional Flow of Aerodynamics

Answer 1

The correct answer is (a) \(\frac {P_e}{P_0}\) < 1

The best explanation: If the stagnation pressure at the inlet is equal to the exit pressure, then there will be no flow in the nozzle as there is no pressure difference for the flow to move. In order to accelerate the air, the pressure difference has to be created by having pe < p0.

Thus the condition to achieve an accelerated flow inside a nozzle is: \(\frac {P_e}{P_0}\) < 1