M15.06 Flashcards
What does the turbine do?
Extracts energy from hot gases which come from the combustion chamber
What are the two different types of turbine?
Radial and axial flow turbine
Where are axial flow turbines used?
Modern gas turbine engines
What’s an advantage of axial flow turbines?
Allow very high airflow
What does the turbine convert?
Gas energy from combustion chamber into turbine torque energy
What must turbine blades withstand at takeoff?
High centrifugal forces of several tons
What is material deformation known as?
Creep
What will be the result of high engine temperatures and speeds?
Increased creep
Why are turbines cooled?
Increase service life, better turbine efficiency
What is the easiest cooling method in HP turbines?
Convection cooling
What’s the best cooling method for the nozzle guide vanes and rotor blades?
Impingement cooling
Where is the film cooling method used?
Nozzle guide vanes at rotor blades
What is the disadvantage of film cooling?
The drill holes are hard to make so very expensive
Active clearance control systems have one or more?
Clearance control valve
What are clearance control valves on modern engines compared to old ones?
Shut off bales on older but modulating on newer
What does tip clearance control save?
Fuel
The turbine section of a twin spool engine typically has?
HPT, LPT, turbine frame
Are HPT cases made in one peice?
Yes
What are the nozzle guide vanes in the HPT held in by?
Nozzle guide vane support
How do you inspect the turbine?
Boroscope
What does the interstage seal act as?
Spacer between tho two discs
What are the blade retainers designed to do?
Hold turbine blades in place
In HPT what is the name for the root of the blade?
Fir tree
What are the two types of blade in modern engine?
Open end blades and shrouded blades
What do shrouded blades reduce?
Vibrations
What seal do shrouded blades have?
Knife edge seal
Where does the air come from to cool the HPT blades?
High pressure compressor
The turbine frame is the …. Major structural component of the engine
Aft
What are the two arrangements for frame struts?
Tangential struts, radial struts
