Turbine Flashcards
Purpose of a Turbine
Extracts energy from gas stream, coverts it to mechanical energy to drive compressors and engine accessories.
What is the most temperature limited and highly stressed component of an engine?
The Turbine
Nozzle Guide Vanes
Guide gas stream at correct angle to gas turbine blades.
Impulse Profile
NGVs are convergent ducts.
Pressure Drop occurs @ NGV
No change of pressure across the Rotor Blades
Reaction Blading
No change @ NGV
Pressure drop at rotor blades
Blade Creep
“High blade temperatures whilst under centrifugal loading.”
Combination of Heat and Strength
Blade Material
Complex Nickel based alloys, single crystal technology, internal/external cooling allowing 200C above melting point.
Active Clearance Control
Hot bled air fed into tubes around turbine casing, causing it to expand.
High Cycle Fatigue
Large number of small stresses
Low Cycle Fatigue
Small number of large tresses
What is the accessory gearbox driven by?
The HP Spool
