Centrifugal and axial compressors are the two main types used in aircraft jet engines. Centrifugal compressors have advantages like being cheap and resistant to foreign object damage, but have limitations like a lower compression ratio. Axial compressors can achieve higher compression ratios but are more complex and prone to stall and surge issues. Both compressor types work by continuously increasing the pressure of air through multiple compressor stages or rows of rotor blades and stator vanes. Anti-surge devices help control airflow and prevent compressor stall and surge.

1. 15.4 COMPRESSORS
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2. CENTRIFUGAL TYPE
SINGLE STAGE COMPRESSOR
TWO STAGE COMPRESSOR SINGLE STAGE DOUBLE ENTRY

3. CENTRIFUGAL ASSY

4. CENTRIFUGAL FEATURES
• ADVANTAGE
– Cheap and simple
– Not prone to FOD and icing
– Stable, no stall and surge
– Large rise in air pressure over distance
• DISADVANTAGE
– Limited compression ration 4:1
– Large frontal area
– Capacity is limit by impaler tip speed
– Easyly loss pressure due to severe change airflow direction

5. AXIAL TYPE
SINGLE SPOOL TWIN SPOOL
TRIPLE SPOOL

6. OPERATING PRINCIPLE
• Continuous compression
through each stage .
• Stage is defined as rotor and
stator
• Its form divergence duct
(continouse pressure rise) in
each stage

7. CASCADE EFFECT
• Ability of the air to travel from low pressure
area to the high prassure area

8. AXIAL ASSY

9. AXIAL FEATURES
• ADVANTAGE
– High compression ratio
– Low fuel consumption
– Small frontal area and high volume of air
– Suit to high thrust
• DISADVANTAGE
– Complicated and expensive
– Poor acceleration
– Very severe to FOD
– Prone to stall and surge

10. COMPONENT
• Rotor Blade :
– Airfoil section and twist to provide correct angle of attack (maintain
uniform airflow)
– Stager angle ( angle of incident of blade)
• Stator Vanes :
– Airfoil section and secure with casing
– Providing divergen blade spacing to effect sec stage compression
– Control direction airflow
• Fan type
– To produce thrust for turbofan engine and to pass air that not
required for combustion
– Engine more quiter and durable using fan
– High aspect ratio : thin and long blade (have clapper support)
– Low aspect ratio : wide chord and smaller blade

11. ROTOR BLADE
Blade Attachment
Blade design

12. STATOR VEIN
Variable stator
Fixed stator

13. FAN
• FAN BALANCING
– Balance to prevent vibration and stress due to
high rotational speed
– Two type of balance:
• Single Plane or Static balance
• Two plane or dynamic balance

14. MIX COMPRESSOR

15. STALL AND SURGE
• Stall :
– Angle of attack of blade become to high or low due to airflow entry
condition.
– Indicate by increase in EGT, vibration and coughing noise
– Transition stall If slight vibration and poor acceleration occur shortly
– Hung stall cause all stage compressor stall and airflow will become
reverse flow (surge)
• Surge :
– Complete breakdown of airflow (all compressor stage stall)
– Due FOD, distored airfoil, bleed valve mailfunction cause the rear
compressor stage chock or exessive pressure ratio
– Indicate by abnormal engine noise, high EGT, vibration, flame emiting
in exhaust
– In extream condition, engine completely destroy

16. AIRFLOW VARIATION

17. AIRFLOW CONTROL
• Anti-surge device
– To prevent or reduce risk stall/surge and maintain
smooth airflow.
– By controlling the movement of airflow or
dumping the unstable airflow from compressor.
– Type :
• Variable intake guide vanes
• Variable stator vanes
• Compressor bleed valve

18. ANTI-SURGE
Variable Inlet guide vanes control
Bleed Valves
Variable stator and actuator mechanism

19. COMPRESSOR RATIO
• Calculated by dividing total pressure after last
stage of compresssion by total inlet pressure.
• Varies with RPM, intake temperature and
blade damage
• Overall pressure ratio for axial compressor is
30:1