The GATE Grind

GATE 2020 AE – Question 25

Propulsion · Intakes and nozzles: non-rotating propulsion components · 1 mark · Multiple choice

For perfectly expanded flow in an aircraft-engine nozzle, exit static pressure equals

  1. Engine-inlet stagnation pressure.
  2. Nozzle-exit stagnation pressure.
  3. Ambient pressure at the nozzle exit.
  4. Nozzle-inlet static pressure.

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Show answer and explanation

Correct answer: (C) Ambient pressure at the nozzle exit.

Explanation

Perfect expansion means the nozzle expands the gas to the surrounding pressure, pe = pa. The pressure-thrust term (pe−pa)Ae is consequently zero. Exit stagnation pressure is generally higher than exit static pressure for moving flow and is not the matching quantity. Select C.

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