Engines Ch4

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Engines Ch4
2012-04-23 23:27:57
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Ch4 book questions
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  1. What does the term "gas generator" mean?
    An engine which is operated by converting the energy of expanding gases into propulsive force
  2. How does a turbojet produce thrust?
    By greatly accelerating a small mass of air and expanding the gases leaving the exhaust nozzle.
  3. How is a turbojet constructed?
    Inlet, compressor, burner, turbine, exhaust nozzle.
  4. What are the + - of the turbojet?
    Best high speed and high altitude performance. Highest TSFC. Longest takeoff rolls.
  5. How is a turbofan constructed?
    Fan, compressor, burner, turbine, exhaust nozzle.
  6. How does a turbofan produce thrust?
    Fan pushes a large mass of air and provides 30-60% of the total thrust.
  7. How much thrust is produced by the fan on a turbofan?
    • 30-60% from the fan.
    • 40-70% from the gas generator exhaust gases.
  8. What is meant by "bypass air?"
    Airflow from the fan "bypassed around the gas generator."
  9. What are tha +- of the turbofan?
    • Better TSFC than a turbojet
    • shorter takeoff distance
    • can lift larger weights

    Large frontal area, slower, and can not fly as high as turbojet.