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Jet Engines: Thrust and Compressors

72 flashcardsby Adam
English
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1
The thrust of a jet engine is directly proportional to the
  • Ratio between N1 and N2
  • Velocity of the exhaust gases
  • Acceleration of the mass of air
2
The compressor shaft rotates on
  • Sintered bearings
  • Ball and roller bearings
  • Plain bearings
3
In a pure jet engine, the rate of pressure rise is greatest at the
  • Compressor stage
  • Combustion stage
  • Turbine stage
4
A DC started motor disconnects due to
  • A centrifugal switch that acts like an overspeed relay
  • Current incresing switching off an overspeed relay
  • Current decresing switching off an overspeed relay
5
For aircrat design purposes, output of a turbo-shaft engine is measured in
  • Thrust horsepower
  • Shaft horsepower
  • Shaft RPM
6
A direct drive turboprop engine
  • Uses a reduction gearbox to reduce RPM of the propeller
  • Uses a single turbine engine
  • Has a direct drive to the propeller
7
If a helicopter rotor /engine RPM gauge shows split reading, the likely cause is
  • Freewheel unit is seized
  • The clutch is slipping
  • A tail rotor drive failure
8
The centrifugal type compressor produces a compression ratio
  • Lower than the axial flow compressor
  • The same as the axial flow compressor
  • Higher than the axial flow compressor
9
A free turbine aircraft engine is most likely to be used on a
  • High bypass engine
  • A helicopter engine
  • A direct coupled engine
10
A free turbine turbo-prop engine has
  • 3 turbine stages driving one shaft
  • 2 turbine stages driving one shaft
  • 2 or more turbine stages driving two shaft
11
A full flow oil system
  • A variable oil pressure dependant upon throttle setting
  • A hot and cold oil pressure limit
  • A single fixed minimum oil pressure
12
A directive drive turbo-prop engine
  • Has a direct drive to the propeller
  • Uses a reduction gearbox to reduce the RPM of the propeller
  • Uses a single turbine only
13
A gas tubine's propulsion force is produced by
  • Reacton of the rearward moving gasses
  • Induced airflow into the engine
  • Impingement of the gasses on the surrounding air
14
A modular constructed gas turbine engine means that
  • Its major assemblies can be removed and replaced
  • The engine is constructed by the vertical assembly technique
  • All engines have a specific component layout
15
A twin spool engine has
  • One turbine on one shaft
  • Two turbines on one shaft
  • Two turbines on two shafts
16
Advantage of flow type fuel system over pressure type fuel system is
  • Has no need for fly weights and governors
  • It can take into account rpm, pressure (ambient) and e.g.t.
  • It has lower pressure so greater reliability
17
An aircraft flying at 800mph would typically use a
  • Turbojet
  • Turbofan
  • Turboprop
18
An annular combustion chamber consists of
  • A series of flame tubes in an air annulus
  • An outer skin and an inner and outer flame skin
  • An air tube and a flame tube
19
During normal running conditions
  • Combustion is self supporting
  • Combustion is contiuously supported by ignition
  • Combustion is intermittently supported by ignition
20
Engines having two independent moving systems are
  • Compound engines
  • Twin spool engines
  • Complex engines
21
Gas turbines work on the
  • Brayton cycle
  • Otto cycle
  • Diesel cycle
22
How are the combustion chambers cooled
  • By fan pressure air
  • By HP compressor air
  • By LP compressor air
23
How is fuel flow varied in a variable displacement pressure type pump
  • Direct cable to camplate
  • Remote servo pressure
  • Alter the camplate angle
24
In a ducted fan engine, the fan is driven by the
  • Turbine
  • Accessory gearbox
  • Air passing over the compressor
25
In a flow type fuel system, fuel shutoff is done by
  • FCU torque motor
  • LP fuel cock
  • Mechanical ball valve
26
In a gas turbine engine, the mass airflow is
  • The mass of airflow through the engine multiplied by the velocity of the airflow
  • The total mass of airflow through the engine
  • The weight of the airflow through the engine multiplied by the tempreature coefficient
27
In a pure jet engine the rate of pressure rise is greatest at the
  • Turbine stage
  • Compressor stage
  • Combustion stage
28
In a single spool gas turbine engine thr compressor rev/min is
  • Equal to the turbine speed
  • More than the turbine speed
  • Less than the turbine speed
29
In a turbine engine used to drive a propeller, the power from the engine is
  • The majority of power is used to drive the prop, with the residual giving a jet reaction
  • The power is diveded equally
  • Majority for jet reaction and the residual to drive the prop
30
In a twin spool engine
  • The HP turbine drives both LP and HP compressors
  • The HP turbine drives the LP compressor and the LP turbine drives the HP compressor
  • The LP turbine drives the LP compressor and the HP turbine drives the HP compressor
31
In the HEIU, the discharge resistors
  • Allows the capacitors to discharge when the unit is switched off
  • Allows sufficient voltage to be stored to provide relight facilities up to 55,000 ft
  • Protects the units from excessive voltages
32
Normal gas turbine engine starting sequence is
  • Starter, ignition, fuel
  • Starter, fuel, ignition
  • Fuell, starter, ignition
33
Oil systems consists of
  • 4 sub-systems
  • 3 sub-systems
  • 2 sub-systems
34
On a gas turbine engine, what is the fan driven by
  • HP turbine
  • LP turbine
  • IP turbine
35
On a twinrotor fan engine, the high pressure turbine drives
  • The N1 gas generator
  • The high pressure compressor and accessory gearbox
  • The fan
36
On a twin spool engine, the HP compressor is driven by
  • Later stages of the turbine
  • Early stages of the turbine
  • RAM air over the compressor
37
One stage of a turbine is
  • NGV then turbine blade
  • Turbine blade then NVG
  • IGV then turbine blade
38
Operation of an engine at a fixed RPM at takeoff (sea-level) causes
  • Low thrust when low tempreature is present
  • Low thrust when high humidity is present
  • Excess thrust when tempreature is high
39
Piston engines work on the
  • Otto cycle
  • Diesel cycle
  • Brayton cycle
40
Power is adjusted in a gas turbine engine by
  • Increasing fuel flow
  • Increasing air and fuel flow
  • Increasing airflow to the combustion chamber
41
Power is adjusted in a variable pitch turboprop aircraft by
  • Increasing RPM
  • Increasing fuel flow
  • Increasing pitch
42
Propelling nozzle provide
  • Pressure and velocity thrust
  • Pressure thrust
  • Velocity thrust
43
Reverse thrust can only be selected when the throttle is
  • 75% power position
  • Open
  • At the idle stop
44
Swirl vanes at the inlet of a combustion chamber
  • Stabilize the flame
  • Increase gas pressure
  • Increase the velocity of the gas
45
The annulus of an axial compressor case is
  • Convergent
  • Parallel
  • Divergent
46
The basic gas turbine engine cycle is
  • Induction, compression, combustion, expansion, exhaust
  • Compression, combustion, induction, expansion, exhaust
  • Induction, compression, expansion, combustion, exhaustThe bleed valve on a engine at start up
47
The bleed valve on a engine at a start up is
  • Open
  • Closed
  • Modulating
48
The centrifugal compressor produces a compression ratio
  • Lower than the axial flow compressor
  • The same as the axial flow compressor
  • Higher than th axial flow compressor
49
The cycle of a gas turbine engine is
  • Completed intwo revolution of the engine
  • Completed in one revolution of engine
  • Continuous
50
The energy remaining in the exhaust or a turbo-shaft engine is
  • 2% of the total energy produced
  • 50% of the total energy produced
  • 20-25% of the total energy produced
51
The fan on a turbofan engine is turned by
  • Induction of the air across the fan into the compressor
  • The combustion chamber gases
  • The turbine section
52
The fuel flow transmitter is downstrem of
  • PRSOV
  • LP pump
  • HP pump
53
The gas tubine cycle is a
  • Constant volume cycle
  • Constant tempreature cycle
  • Constant pressure cycle
54
The high bypass duct
  • Improves propulsive efficiency
  • Drives a cabin air compressor
  • Provides engine cooling
55
The HP compressor is powered by
  • The first set of turbines
  • The last set of turbines
  • The intermediate compressor
56
The inlet of a turbo fan is
  • Convergent - Divergent
  • Convergent
  • Divergent
57
The largest pressure change in air passing through an engine occurs in the
  • Compressor of a turbojet engine
  • Propelling nozzle of a turboshaft engine
  • Turbine of a turboprop engine
58
The majority of power in a free turbine engine is used to
  • Expel gases through the exhaust
  • Drive the free turbine
  • Drive the gas generator
59
The majority of the output power from a turbofan is in the form of
  • Torque
  • Neither thrust nor torque
  • Thrust
60
The purpose of a high bypass ducted fan engine is to
  • Improve thrust
  • Improve efficiency
  • Reduce size
61
The purpose of the LP fuel pump is to
  • Pump fuel from the aircraft fuel tanks to the engine
  • Ensure the fuel flow govenor gets enough fuel
  • Ensure the HP fuel pump does not cavitate
62
Thrust is generated in a turboprop system by
  • Moving a large mass of air quickly
  • Moving a small mass of air quickly
  • Moving a large mass of air slowly
63
Thrust of a jet turbine engine is directly proportional to the
  • Velocity of the exhaust gases
  • Acceleration of the mass of air
  • Ration between N1 and N2
64
Turboprop shaft bearings are
  • Plain
  • Sintered
  • Roller or pin
65
What does a 'stage' consist of
  • Rotor and stator
  • Stator
  • Rotor
66
What drives the high pressure compressor
  • Nearest turbine
  • All turbines combined
  • Furthest away turbine
67
What is an engine stage
  • One compressor rotor and one nozzle guide vane
  • One rotor plus one stator
  • One IGV and one rotor
68
What is the pressure increase over one stage of a centrifugal compressor
  • 1:2:1
  • 8:1
  • 5:1
69
What is unit of measurement of EGT
  • 'C
  • 'K
  • 'F
70
What percentage of air passing through combustion section is burned
  • 50%
  • 40%
  • 75%
71
When the air iss blocked in the HP compressor
  • EPR and TGT both decrease
  • EPR and TGT both remain the same
  • EPR decreases and TGT increases
72
Which of these statements is true regarding the Brayton cycle
  • Pressure energy is added to the working medium at compression
  • Heat energy is added to the working medium at combustion
  • Both of the other answere are correct
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