Gasturbine Performance Deel 2
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The purpose of a turbine is to extract (1) … from the gas so it can deliver work to drive the compressor, and possibly the fan or propeller. The specific power supplied by the gas is the largest by (2) … turbine.

  • (1) enthalpy (2) a reaction
  • (1) enthalpy (2) an impulse (correct)
  • (1) kinetic energy (2) a reaction
  • (1) kinetic energy (2) an impulse

    • Passive Clearance Control (PCC) means cooling the:

  • house of the HPT
  • house of the LPT
  • turbine blades (correct)
  • wheels of the turbine

    • The tension in a turbine blade caused by the centrifugal force is the largest at the … the leading- and trailing edge.

  • tip, at
  • root, at
  • tip, halfway
  • root, halfway (correct)

    • The result of fatigue is a crack, occurring as a result of a:

    <p>periodically fluctuating load</p> Signup and view all the answers

    At what fuel-air ratio at the beginning of the combustion chamber will the NOx-production in the entire combustion chamber be the lowest?

    <p>1:16</p> Signup and view all the answers

    What type of combustion chamber is the most suitable for the construction of a compact engine?

    <p>Reversal</p> Signup and view all the answers

    Both a … make the use of high-pressure air from the APU at start-up unnecessary.

    <p>jet starter and electric starting engine</p> Signup and view all the answers

    The following four events take place at the start-up of the engine: (I) turn on fuel flow (II) turn on detonator (III) reaching idle velocity (IV) shut-off the starting engine In what order?

    <p>II, I, IV, III</p> Signup and view all the answers

    At start-up, the N2-shaft is set in motion by the:

    <p>starting engine</p> Signup and view all the answers

    What is the last parameter to increase at the start-up of the engine?

    <p>EGT</p> Signup and view all the answers

    During take-off, approximately 12% more air flows through the engine than during cruise. How much more fuel does that cost according to the graph?

    <p>0.65</p> Signup and view all the answers

    One of the prohibited areas in the fuel metering graph is labelled as ‘Over Temp Area’. What problem does arise in this area?

    <p>The fuel-air ratio increases too much, resulting in a TIT that is too high.</p> Signup and view all the answers

    The heat exchanger heats the fuel to: (I) avoid the formation of ice crystals (II) prevent a shut-down of the pump in the fuel tank

    <p>(I) is right, (II) is wrong</p> Signup and view all the answers

    What signal is NOT used by an MEC?

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

    Because the gas flow of a turbofan at the outlet has a lower (1) …, it has at the same TAS, a (2) … propulsive efficiency than a turbojet.

    <p>(1) velocity (2) higher</p> Signup and view all the answers

    The gas in cylinder number 3 leaves the cylinder. In cylinder number 2 the gas:

    <p>is compressed</p> Signup and view all the answers

    No (1) … during an (2) … process.

    <p>(1) heat exchange with the environment takes place (2) isentropic</p> Signup and view all the answers

    If we increase the RPM of a reciprocating engine and do not change the fuel-air ratio, then the work done (1) … and the SPECIFIC work done (2) …

    <p>(1) increases (2) stays the same</p> Signup and view all the answers

    Place the engine types below in order of decreasing aircraft velocity.

    <p>3-2-4-1</p> Signup and view all the answers

    What thermodynamic processes take place in a IDEAL turbojet?

    <p>Isentropic and isobaric</p> Signup and view all the answers

    At what modules we find the highest efficiencies?

    <p>Inlet and outlet</p> Signup and view all the answers

    When the BPR is decreases the propulsive efficiency will (1) … and the thermal efficiency will (2) …

    <p>(1) decrease (2) stay the same</p> Signup and view all the answers

    A drum-type rotor is … compared to a disc-type rotor.

    <p>lighter and more vulnerable</p> Signup and view all the answers

    A twist is a change in the … at different blade heights.

    <p>blade angle to compensate for a change in rotational velocity (𝑣𝑟𝑜𝑡𝑜𝑟 )</p> Signup and view all the answers

    During the progress of the start-up of the gas turbine engine on the ground the VBVs (1) … and the VSVs (2) …

    <p>(1) close (2) open</p> Signup and view all the answers

    In an impulse turbine the degree of reaction is:

    <p>0</p> Signup and view all the answers

    A kerosine-air mixture has a stoichiometric ratio. That is, we need (1) … of air for (2) … of kerosine.

    <p>(1) 15 kg (2) 1 kg</p> Signup and view all the answers

    If no … are present, then the start-up-cycle can be initiated with the help of a battery.

    <p>GPU and jet starter</p> Signup and view all the answers

    What is a dry start?

    <p>The engine refusing to start due to a problem with the fuel supply</p> Signup and view all the answers

    The risk to end up in the stall area of the fuel metering graph is the largest when you (1) … when there is a (2) … ambient temperature.

    <p>(1) accelerate (2) low</p> Signup and view all the answers

    How many pumps does the fuel pass from tank to fuel nozzle?

    <p>3</p> Signup and view all the answers

    What does the ECU of the FADEC NOT control?

    <p>Landing gear</p> Signup and view all the answers

    What illustration gives the correct sizes and directions of the forces of airflow on the engine and the engine on the airflow?

    <p>Fairflow on engine midden Fengine on airflow</p> Signup and view all the answers

    The propulsive efficiency is the ratio between the power absorbed by the (1) ... and the power delivered by the (2) …

    <p>(1) airplane (2) engine</p> Signup and view all the answers

    In a reciprocating Diesel engine, energy is released during an ... process.

    <p>isobaric</p> Signup and view all the answers

    A Diesel engine has a (1) … efficiency than a gasoline engine. That is partly because the Diesel engine has a much (2) … compression ratio than a gasoline engine.

    <p>(1) higher (2) higher</p> Signup and view all the answers

    The (1) … is powered by the (2) …

    <p>(1) compressor (2) turbine</p> Signup and view all the answers

    Which form of energy is included in total enthalpy, but NOT in enthalpy?

    <p>Kinetic energy</p> Signup and view all the answers

    In the last part of a high-bypass turbofan, due to the convergence of the outlet the (1) ... of the air (2) ...

    <p>(1) temperature (2) decreases</p> Signup and view all the answers

    What should be the pressure's value at the end of the compressor to achieve the highest possible thermal efficiency?

    <p>As high as possible</p> Signup and view all the answers

    The critical pressure increases by the ... of the outlet.

    <p>increase of the pressure of the gas at the beginning</p> Signup and view all the answers

    (I) By increasing the CPR, the TSFC increases (II) By increasing the Mach number, the TSFC increases

    <p>(I) wrong (II) right</p> Signup and view all the answers

    (I) When the BPR is increased, the propulsive efficiency will decrease (II) When the BPR is increased, in general, the thermal efficiency will increase

    <p>(I) wrong (II) wrong</p> Signup and view all the answers

    … gives the most robust connection between the disc and the rotor blade.

    <p>An axial firtree</p> Signup and view all the answers

    The amount of power that is transferred to the air in an axial compressor stage, is smaller than that extracted from the gas in a turbine stage. A factor which does NOT contribute to this, is the smaller ... in the compressor.

    <p>mass flow</p> Signup and view all the answers

    What conclusion can you draw if the degree of reaction of a compressor's stage increases?

    <p>The pressure build-up over the rotor increases relative to that of the stator.</p> Signup and view all the answers

    An axial compressor has significantly more stages than a turbine. This is because ...

    <p>in the compressor the pressure increases whilst in the turbine it decreases.</p> Signup and view all the answers

    The purpose of the VBVs is …

    <p>to prevent blockage of the airflow when exiting the LPC</p> Signup and view all the answers

    If we compare the stage of a radial compressor with that of an axial compressor, then at the stage of the radial compressor the …

    <p>frontal area is relatively large</p> Signup and view all the answers

    Crack (on a rotor blade) is a result of fatigue, which occurs as a result of a …

    <p>periodically fluctuating load</p> Signup and view all the answers

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