Lecture 22 Flashcards
What does bypass air do?
Create thrust
Cool the core engine
Noise suppression
What are the types of combustors/burners?*
Multiple-can
Can-annular
Annular
What are advantages and disadvantages of multiple-can combustors/burners?*
Advantage:
Individual cans can be removed
Disadvantages:
Uneven temperatures
Can cause turbine failure when cans fail due to extreme temperature differences
What are advantages and disadvantages of can-annular combustors/burners?*
Advantages:
Individual cans can be removed
Shorter cans (lower pressure drop)
Uniform temperatures even with a clogged fuel nozzle
What are advantages and disadvantages of annular combustors/burners?*
Advantages:
No cans
Makes the most efficient use of space
Efficient mixing of fuel with air
Requires minimum amount of cooling air
Provides even temperature air
Disadvantage:
Cannot be replaced without removing the engine from the aircraft
What is the power-producing component in a turbine engine?
Turbine section
What type of duct (divergent/convergent) is the turbine section?*
Divergent
What is the hottest section in a turbine engine?*
What measures this temperature?*
Turbine inlet guide vanes
Turbine Inlet Temperature (TIT)
Where are the turbine inlet guide vanes?*
Between the combustion section and first stage turbine
What is it called when the turbine disk and blades are machined out of a single piece of material?
Blisk
What limits the amount of power a gas turbine engine can produce?
How can you improve efficiency?
The maximum temperature the turbine inlet can tolerate
Turbine cooling
What are the three main causes of turbine failure? Explain each.
Creep: deformation of metal that is continually under high centrifugal loads and temperatures
Metal Fatigue: weakening of metal subjected to repeated cycles
Corrosion: alloying agents combine with elements in the air to form salts
How are exhaust gases utilized to produce thrust?
Exhaust system straightens and accelerates the exhaust gases using a convergent duct
What are variable-area nozzles?
How do modern engine control these nozzles verses older engines?
Used for turbine engines equipped with afterburners
Opens or closes (contracts) automatically based on the fuel flow of the engine to maintain optimum back pressure
Earlier afterburner engines had only two positions
Modern afterburner engines control nozzles with the electronic engine control (EEC)
What dictates the amount of noise that can be heard from an engine?
How can you decrease noise levels without sacrificing thrust?
The velocity of the exhaust gases
Frequency of the sound (low frequency is louder)
Increasing the frequency
