M15.6 Turbine Section Flashcards
(33 cards)
Types of turbines
- Radial flow
- Axial flow
How many stages to a Radial flow turbine
Always a single stage
Advantage and disadvantage of radial flow turbine
Adv - Simple and easy to manufacture
Dissad - Less efficient
Duct shape between NGV and turbine blades
Convergent
Name of turbine which only uses the impact of the gas flow
Impact turbine
When does turbine creep occur
When centrifugal loads are applied over a long period of time
Do the turbine blades return to the same shape after turbine creep
No, it goes into the inelastic region
What can cause an increase in the rate of creep
High engine speeds and temp
What is the function of centrifugal force, material temp and time named
Creep
Easiest method of HPT cooling
Convection
Where is HOT cooling used
- At the turbine NGV
- Turbine rotor blades
Most effective type of turbine cooling
Film cooling
Disadvantage of film cooling
Difficult to drill holes so expensive
What is used to cool NGV and first stage rotor blades
- Convection
- Impingement
- Film cooling
What is used to cool second stage NGVs
- Convection
- Impingement
How much tip clearance can cause a 1% fuel increase
0.25mm or 0.01”
How much fuel is used with a 1% fuel increase
Approx 30,000kg per engine
What expands faster in the turbine
Turbine casing
What air is used in active clearance control
Fan or compressor bleed
Types of clearance control
Active
Passive
Where is air from the fan used in passive clearance control
LP turbine
Difference between active and passive clearance control
Active controls the amount of air used
If HP compressor air is used for ACC where is the air taken from
Intermediate stages or the last stages
What controls and actuates active clearance control valves
- ECU controlled
- HMU actuated
