M15.4 Compressors Flashcards
(14 cards)
What two components are in compressor and what creates a stage
What is a stage in relation to a axial compressor
Rotor and shaft
What improves airflow to the fist stage
Inlet guide vanes (IGVs)
What components make up a centrifugal compressor
Impeller (rotor)
Diffuser (stator)
Compressor manifold
What is the compression ratio of an axial and centrifugal compressor
Axial: between 1:1 and 1:2
Centrifugal: 8:1
What is the difference in stages in axial and centrifugal compressors
Axial: number of stages is based on desired pressure
Centrifugal: max 2
What three factors affect centrifugal forces in fan blades
Rotor speed
Blade mass
CoG
What may moment weight be given in
Gram inches
Cm.g
Once inches
Where can you find moment weight on the blade
Blade root
How is fan blade 1 identified
Index mark or offset hole
What are the two methods of changing a blade
Replace new with the closest moment weight. Balding weights can be used if out of tolerances
Replace a pair of blades with same moment weight opposite one another
What affects angle of attack (AoA)
AoA increase when, rotor speed increase, and inlet velocity decreases
AoA decrease when, rotor speed decreases, and inlet velocity increases
Methods to avoid stall
Compressor bleed valves - mid section and are open at low engine speeds
Multiple spools
Variable compressor stator vanes - most effective
What is a compressor surge
Aggressive form of stall, and air travels fwd through the comprossor
