Turbine Hot Section Flashcards
The hot section comprises of?
Combustion section
Turbines
Exhaust
Primary vs secondary air
Primary air is used for combustion
Secondary air is used for cooling
What are the 4 types of combustor designs?
Can
Can-annular
Annular
Reverse-flow annular
What is the main purpose of a turbine?
To drive the compress or propeller/fan
How do you extract more power from a turbine?
add turbine stages
Where is the temperature of gases the highest?
As they enter the first stage of turbine
Where is the highest velocity of a turbine?
As they leave the turbine
What are stator blades?
Fixed blades to direct the air so it will enter the turbine blades at the optimum angle.
Also decrease pressure and increase velocity
What the most common way turbine blades are attached?
Fir-tree method
What are the three types of turbine blades?
Impulse
Reaction
Impulse-reaction
What are impulse blades?
Shaped like buckets
No change in velocity
What are reaction blades?
Shaped like airfoils
Increase velocity
Types of turbine failures?
Creep
Metal fatigue
Corrosion
What is creep?
Deformation of metal due to continuous centrifugal loads and high temperatures
What is metal fatigue?
Due to repeated cyclic loading
What is corrosion?
Accelerated by high temperature
What are the two ways of driving accessory systems?
Using compressor bleed air
Driven by the compressor drive shaft through gears
What type of engine is an APU
Turboshaft
What is the purpose of a APU?
A device that provides energy for functions other than propulsion
How does an APU work?
It drives a generator, that may provide pressurized bleed air for ground heating and cooling the cabin, may supply an an auxiliary hydraulic system
What is the function of an APU?
Electric power
Pneumatic power
Hydraulic pressure
Why is the hot section subjected to more severe stresses?
Its subjected to high temperature exposure