EASA Part 66 Module 15.4 : Compressors

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EASA Part 66 Module 15.4 : Compressors

  1. 1. 15.4 COMPRESSORS http://part66.blogspot.com/
  2. 2. CENTRIFUGAL TYPE SINGLE STAGE COMPRESSORTWO STAGE COMPRESSOR SINGLE STAGE DOUBLE ENTRY
  3. 3. CENTRIFUGAL ASSY
  4. 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. 5. AXIAL TYPESINGLE SPOOL TWIN SPOOL TRIPLE SPOOL
  6. 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. 7. CASCADE EFFECT• Ability of the air to travel from low pressure area to the high prassure area
  8. 8. AXIAL ASSY
  9. 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. 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. 11. ROTOR BLADE Blade AttachmentBlade design
  12. 12. STATOR VEIN Variable statorFixed stator
  13. 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. 14. MIX COMPRESSOR
  15. 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. 16. AIRFLOW VARIATION
  17. 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. 18. ANTI-SURGEVariable Inlet guide vanes control Bleed Valves Variable stator and actuator mechanism
  19. 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

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