15.6* Flashcards
Where is the highest heat to metal contact in the engine?
1st stage HP turbine
What are the different types of turbine blades called?
Impulse and impulse reaction
What 3 factors contribute to turbine creep?
Time
Temperature
Centrifugal force
How is vibration reduced in LP turbine blades?
Use of shrouds
What causes stress rupture cracks in the turbine section?
Metal fatigue and corrosion
When does the active clearance control systems operate on engines fitted with hydro mechanical fuel control systems?
During climb and cruise
What type of duct does a nozzle guide vane form with adjacent vanes?
A convergent (nozzle) duct
What are the methods used to cool NGV’s and HP turbine blades?
1st stage of nozzle and blades use convection, impingement and film
2nd stage nozzle uses convection and impingement
2nd stage blades use convection
What method is used to cool the LP turbine blades?
LP turbine blades are not normally cooled
What is the most common method of attaching turbine rotor blades?
Fir tree root
What advantage does the axial flow turbine have over the radial flow turbine?
They can be built with as many stages as required and they allow for very high flow rate
What is the purpose of the turbine?
To create torque used to drive the compressor
What is the primary air sources for a passive clearance control system?
HPC air for the HPT
Fan air for LPT
On engine shut down what is the contraction sequence of the turbine in the casing?
The rotor shrinks faster due to reduction in centrifugal force then the casing shrinks faster due to it’d thinner material
On what stages of a turbine would open turbine blades normally be found?
On the HP turbine stages
