Exhaust and Thrust Reversers
What this domain tests
This domain tests exhaust nozzle function, exhaust cone and strut hardware, and thrust-reverser types and logic. Expect questions on nozzle pressure ratio, reverser deployment, and the effect of exhaust blockage or leaks.
Core rules
- A convergent nozzle accelerates exhaust to sonic speed at the throat; a convergent-divergent nozzle can expand supersonic flow and recover pressure thrust.
- Exhaust cone and turbine rear frame struts straighten and guide the flow; cracks or distortion can affect EGT and vibration.
- Thrust reverser types include target (bucket), cascade, and cold-stream. They redirect flow forward, producing reverse thrust; they do not reverse engine rotation.
- Deployment is interlocked: thrust lever, air/ground logic, and engine parameters must be valid. In-flight deployment is prohibited on most transport engines.
Worked example
A reverser produces 30 kN of forward thrust at takeoff and 12 kN of reverse thrust at the same lever angle. Reverse thrust is 12/30 = 40% of forward thrust. If the reverser is stowed asymmetrically on one engine, a yawing moment is produced; the reasoning is that reverse thrust acts forward on one side and forward thrust on the other, creating a couple about the aircraft centerline.
Traps
Saying reverse thrust reverses the fan; assuming full reverse is available at high forward speed; ignoring the difference between cascade and target reversers; overlooking EPR changes when a reverser leaks.