FAA Aviation Mechanic Powerplant (AMP)Turbine EnginesMedium
A turbine blade is manufactured with small holes along its leading edge and surface through which cooling air is discharged to create a protective layer of cooler air over the blade surface. This describes which turbine blade cooling method?
- AConvection cooling
- BFilm cooling
- CRadiation cooling
- DImpingement cooling
Show answer & explanationAnswer & explanation
Correct answer: B. Film cooling
Film cooling discharges cooling air through discrete holes on the blade surface, forming a thin protective film of cooler air between the blade metal and the hot combustion gases.
Why the other options are wrong
- A. Convection cooling relies on air flowing through internal passages, not surface film.
- C. Radiation cooling is not a recognized turbine blade cooling method.
- D. Impingement cooling directs jets of air against the inside of the blade wall.
Turbine Blade Cooling
Methods used to keep turbine blades below their material limits despite exposure to extremely hot combustion gases, including convection, impingement, and film cooling.
- Convection: air flows through internal blade passages
- Impingement: air jets strike internal blade walls
- Film: air exits surface holes forming a cooling film
Memory trick: 'Film wraps a blanket over the blade' - film cooling forms a surface layer