50 Questions
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) an impulse
Passive Clearance Control (PCC) means cooling the:
turbine blades
The tension in a turbine blade caused by the centrifugal force is the largest at the … the leading- and trailing edge.
root, halfway
The result of fatigue is a crack, occurring as a result of a:
periodically fluctuating load
At what fuel-air ratio at the beginning of the combustion chamber will the NOx-production in the entire combustion chamber be the lowest?
1:16
What type of combustion chamber is the most suitable for the construction of a compact engine?
Reversal
Both a … make the use of high-pressure air from the APU at start-up unnecessary.
jet starter and electric starting engine
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?
II, I, IV, III
At start-up, the N2-shaft is set in motion by the:
starting engine
What is the last parameter to increase at the start-up of the engine?
EGT
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?
0.65
One of the prohibited areas in the fuel metering graph is labelled as ‘Over Temp Area’. What problem does arise in this area?
The fuel-air ratio increases too much, resulting in a TIT that is too high.
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
(I) is right, (II) is wrong
What signal is NOT used by an MEC?
N1
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.
(1) velocity (2) higher
The gas in cylinder number 3 leaves the cylinder. In cylinder number 2 the gas:
is compressed
No (1) … during an (2) … process.
(1) heat exchange with the environment takes place (2) isentropic
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) …
(1) increases (2) stays the same
Place the engine types below in order of decreasing aircraft velocity.
3-2-4-1
What thermodynamic processes take place in a IDEAL turbojet?
Isentropic and isobaric
At what modules we find the highest efficiencies?
Inlet and outlet
When the BPR is decreases the propulsive efficiency will (1) … and the thermal efficiency will (2) …
(1) decrease (2) stay the same
A drum-type rotor is … compared to a disc-type rotor.
lighter and more vulnerable
A twist is a change in the … at different blade heights.
blade angle to compensate for a change in rotational velocity (𝑣𝑟𝑜𝑡𝑜𝑟 )
During the progress of the start-up of the gas turbine engine on the ground the VBVs (1) … and the VSVs (2) …
(1) close (2) open
In an impulse turbine the degree of reaction is:
0
A kerosine-air mixture has a stoichiometric ratio. That is, we need (1) … of air for (2) … of kerosine.
(1) 15 kg (2) 1 kg
If no … are present, then the start-up-cycle can be initiated with the help of a battery.
GPU and jet starter
What is a dry start?
The engine refusing to start due to a problem with the fuel supply
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.
(1) accelerate (2) low
How many pumps does the fuel pass from tank to fuel nozzle?
3
What does the ECU of the FADEC NOT control?
Landing gear
What illustration gives the correct sizes and directions of the forces of airflow on the engine and the engine on the airflow?
Fairflow on engine midden Fengine on airflow
The propulsive efficiency is the ratio between the power absorbed by the (1) ... and the power delivered by the (2) …
(1) airplane (2) engine
In a reciprocating Diesel engine, energy is released during an ... process.
isobaric
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.
(1) higher (2) higher
The (1) … is powered by the (2) …
(1) compressor (2) turbine
Which form of energy is included in total enthalpy, but NOT in enthalpy?
Kinetic energy
In the last part of a high-bypass turbofan, due to the convergence of the outlet the (1) ... of the air (2) ...
(1) temperature (2) decreases
What should be the pressure's value at the end of the compressor to achieve the highest possible thermal efficiency?
As high as possible
The critical pressure increases by the ... of the outlet.
increase of the pressure of the gas at the beginning
(I) By increasing the CPR, the TSFC increases (II) By increasing the Mach number, the TSFC increases
(I) wrong (II) right
(I) When the BPR is increased, the propulsive efficiency will decrease (II) When the BPR is increased, in general, the thermal efficiency will increase
(I) wrong (II) wrong
… gives the most robust connection between the disc and the rotor blade.
An axial firtree
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.
mass flow
What conclusion can you draw if the degree of reaction of a compressor's stage increases?
The pressure build-up over the rotor increases relative to that of the stator.
An axial compressor has significantly more stages than a turbine. This is because ...
in the compressor the pressure increases whilst in the turbine it decreases.
The purpose of the VBVs is …
to prevent blockage of the airflow when exiting the LPC
If we compare the stage of a radial compressor with that of an axial compressor, then at the stage of the radial compressor the …
frontal area is relatively large
Crack (on a rotor blade) is a result of fatigue, which occurs as a result of a …
periodically fluctuating load
Test your knowledge of gas turbine components, performance, and combustion chambers with this quiz. Questions cover topics such as turbine function, passive clearance control, blade tension, NOx-production, and combustion chamber types.
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