15.4 Compressors Flashcards
(25 cards)
What is the main function of a compressor?
To supply sufficient air to the combustion chamber
What is the function of the IGV and OGV?
To improve airflow
What are the 2 types of compressors?
Centrifugal and axial flow
What type of compressor is used on turbofan engines?
Axial flow
What type of compressor is used on turboprop and turbo shaft engines?
Centrifugal
What is the maximum amount of stages a centrifugal compressor can have?
2
What is the maximum amount of stages an axial flow compressor can have?
Unlimited
How does an axial flow compressor maintain axial velocity?
By gradually reducing drum area
What is the ratio of an axial flow compressor?
1:1 or 1:2
What is the ratio of a centrifugal compressor?
8:1
What 2 stages make up a compressor manifold on a centrifugal compressor?
Impeller + diffuser
What are the 2 types of impeller?
Single entry and double entry
What 3 things do centrifugal forces depend on?
Rotor speed, blade mass and distance of centre of gravity to rotational axis
What is the moment weight equal to?
The sum of blade mass and distance of contra of gravity to rotational axis
Where can the moment weight be found on the blade?
Blade root
What direction are blades OFTEN numbered?
Direction of rotation
Where does a compressor surge most often occur?
Fwd or aft compressor section
What happens to the air velocity when angle of attack increases
Decreases
What are the 3 methods to avoid compressor stall and surge?
Bleed valves, 2 or 3 spool rotors or variable stator vanes
Where are bleed valves located?
Mid to aft compressor section
Where are variable stator vanes located?
Fwd compressor section
What is a compressor stage?
Rotor then stator
What is the function of a rotor?
Increases energy of airflow
What is the function of a stator?
Increases pressure of airflow
