Jet Engine Thrust: Newton's Second Law
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Questions and Answers

What does N1, or %N1, denote in a jet engine?

  • The compressor's rotation rate
  • The medium-speed rotor's rotation rate
  • The rotation rate of the high-speed rotor
  • The rotation rate of the low-speed rotor (correct)
  • What is the corrected N1 calculated by dividing?

  • %N1 by the engine's RPM
  • %N1 by the airflow rate
  • %N1 by the pressure ratio
  • %N1 by the total temperature ratio raised to some power (correct)
  • What type of engine uses %N1 as the primary thrust setting parameter?

  • Rolls Royce engines
  • General Electric and CFMI engines (correct)
  • Three-spool engines
  • Two-spool engines
  • What is engine stall also known as?

    <p>Compressor stall</p> Signup and view all the answers

    What is surge in a jet engine?

    <p>A condition of unsteady airflow through the engine</p> Signup and view all the answers

    What can cause a flameout in a jet engine?

    <p>Unsteady airflow through the engine</p> Signup and view all the answers

    What is bleed in a jet engine?

    <p>Extraction of compressed air from the engine</p> Signup and view all the answers

    In a two-spool engine, what does N2 denote?

    <p>The rotation rate of the high-speed rotor</p> Signup and view all the answers

    What does %RN1 represent?

    <p>The corrected N1</p> Signup and view all the answers

    What is the relationship between gauge N1 and corrected N1 dependent on?

    <p>The engine type</p> Signup and view all the answers

    Study Notes

    Thrust Equation

    • Net thrust (Fnet) equation: mass flow rates and velocities.
    • Force equation: F = w * g * (V2 – V1), relating force, gas flow, gravity, and initial/final gas velocities.

    Factors Affecting Thrust

    • Air density, a function of temperature and pressure altitude, is a significant component affecting thrust
    • Other factors include engine design limitations, such as pressure differential across the engine case, turbine inlet temperature, and fan speed

    Thrust Settings and Ratings

    • Maximum Takeoff Thrust: the highest thrust level available from an engine, certified and time-limited to a maximum of 5 minutes (extendable to 10 minutes for one-engine inoperative takeoff)
    • Go-Around Thrust: a certified rating
    • Maximum Continuous Thrust (MCT): a certified rating
    • Maximum Climb Thrust (MCLT) and Maximum Cruise Thrust (MCRT): not certified ratings

    Engine Parameters

    • Engine Pressure Ratio (EPR): the ratio of the total pressure at the exhaust to the total pressure in front of the fan
    • Percent of Fan Reference RPM (%N1): the percentage of the reference rotation speed of the fan

    Common Jet Engine Terms

    • Corrected N1 (or Referred N1): N1 divided by the total temperature ratio raised to some power
    • N2 and N3: the rotation rates of the medium-speed and high-speed rotors of a three-spool engine
    • Engine Stall (compressor stall): a condition characterized by stalled airflow over the compressor blades
    • Surge: a condition of unsteady airflow through an engine due to abnormal flow conditions
    • Flameout: a condition in which the combustion chambers lose their ignition
    • Bleed: the extraction of compressed air from the engine

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    Description

    Learn about the thrust equation in jet engines, derived from Newton's second law of motion. Understand the variables involved and how they affect the thrust of a jet engine.

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