FAA Aviation Mechanic Powerplant (AMP)Turbine EnginesMedium
A subsonic turbofan engine is fitted with a fixed convergent exhaust nozzle. What effect does this nozzle design have on the exhaust gases as they pass through it?
- AVelocity decreases and static pressure increases toward the exit
- BVelocity increases and static pressure decreases toward the exit
- CBoth velocity and static pressure remain constant through the nozzle
- DBoth velocity and static pressure increase toward the exit
Show answer & explanationAnswer & explanation
Correct answer: B. Velocity increases and static pressure decreases toward the exit
A convergent nozzle narrows in the direction of flow, which for subsonic flow accelerates the gas while static pressure drops, converting pressure energy into kinetic energy to produce thrust.
Why the other options are wrong
- A. This describes a diffuser, not a convergent nozzle.
- C. A nozzle is designed specifically to change velocity and pressure.
- D. Pressure does not increase in a converging subsonic nozzle.
Convergent Exhaust Nozzle
A nozzle that decreases in cross-sectional area toward the exit, accelerating subsonic exhaust gas while reducing static pressure.
- Used on most subsonic turbofans
- Converts pressure energy to velocity
- Divergent sections needed for supersonic acceleration
- Nozzle shape affects thrust efficiency
Memory trick: Convergent = squeeze to speed up, like pinching a hose