10 Feb 2014

Jet Engine (CT) Question Bank PAPER 3

1. Blade is an angle formed by a line perpendicular to the propeller shaft and line formed by the

(a)    Relative wind
(b)   Apparent wind
(c)    Chord of the blade
(d)   Blade face

2. Thrust produced by a rotating propeller is a result of
(a)    Propeller slippage
(b)   An area of low pressure behind the propeller
(c)    An area of decreased pressure immediately in front of the pressure blades
(d)   The angle of relative wind and rotational velocity wind and rotational velocity of the propeller

3. Propeller blade station number increase from
(a)    Huh to tip
(b)   Tip to hule
(c)    Leading edge to aft edge
(d)   Aft edge of leading edge

4. It should have high specific gravity
(a)    Low pan point

5. Velocity index should be high. High freezing point – at a cold atm the water contents in the fuel in having tendency to form in a ice crystal

6. It should be filtered to jet engine
(a)    It should have low carbon content after burning the fuel

7. In twin spool engine, with constant N2, compressor inlet temperature is decreasing then
(a)    N2 changes
(b)   Fuel flow increases
(c)    N1 decreases
(d)   The ratio N1 is maintained constant
   N2

8. The thrust developed by high bypass ratio engine is
(a)    Indicated by EGT
(b)    Indicated by N2
(c)    Proportional fan speed
(d)   Not affected by ambient conditions





9. Perceived noise decibel (PNDB) level is low in case of
(a)    Pure jets without noise suppressor
(b)   Straight jet with noise suppressor
(c)    Low by pass jets
(d)   High by pass jets with acoustic panel

10.  Ignitor plug spark is due to
(a)    High frequency
(b)   High input current
(c)    Discharge (storage) capacitor
(d)   DC voltage

11. In a ‘hot tank’ oil system
(a)    Oil cooler is not provided
(b)   Oil is stored in a separate tank
(c)    Oil is at high temp in the tank
(d)   De-aerator effect is very slow

12. If jet velocity and mass flow is constant for a jet engine then thrust
(a)    Is maximum when aircraft speed is minimum
(b)   Is maximum when aircraft speed is maximum
(c)    Is more when jet velocity and inlet velocity are equal
(d)   Is always constant

13.  Water injection systems are provides for the jet engine for the thrust augmentation the thrust augmentation for water injection can be caused and by two methods.
(a)    By adding or injecting water at the compressor inlet
(b)   By adding or injecting water at the differ section 

Fig shown that a water tank made up of aluminum or sheet metal allows the water flow a regulating

It then panes to the pressure regulating V/o of the diffuse and compressor inlet thought which water injection in done by providing two manifolds at the diffuse and compressor manifold.

A water heater is provided for the water to not formed ice in cold atm or cold weather condition

A drain a/v provided to drain full water tank after are it is generally use of after getting sufficient thrust by water injection

Water injection system used when aircraft an going to take off



14. In a compressor space between surge line and working lines called
(a)    Safety margin on surge margin
(b)   Stable zone unstable zone
(c)    Unstable zone
(d)   Stagger zone

15. Hottest zone in turbine engine is
(a)    Compressor outlet
(b)   Turbine
(c)    1st stage NGV
(d)   Exhaust nozzle

16. In a high by pass engine NGV’s are eliminated
(a)     To reduced noise
(b)    To reduce weight
(c)     To increase efficiency
(d)    To satisfy 1 and 2 above

For maximum thrust
            The thrust augmentation is achieved a the compressor inlet by injecting water at the compressor inlet which increases mass airflow and their by thrust

            Thrust augmentation is achieved a the diffuser section by injecting water at the diffuser section and which als the diffuser section and decreases the temperature of the diffuser section which gives high deme man airflow high affect to maximum

17. Brayton cycle is
(a)    Constant temperature cycle
(b)   Constant volume cycle
(c)    Constant pressure and constant temperature cycle

18. NGV’s of turbine are usually
(a)    Hollow
(b)   Solid
(c)    Air cooled
(d)   As per (1) & (2) above

19. Most common defects in combustion chamber is
(a)    Crack and burning
(b)   Scoring
(c)    Pitting
(d)   Blistering




20. Jet engine ignition system.
Jet engine ignition system is a high intensity and dual capacitor discharge type are used
            The two system are used for the ignition system
(a)    Low voltage A.C or D.C type ignition system
(b)   High voltage capacitor discharge type ignition system

21. High voltage capacitor discharge type ignition system
FIGURE SHOWN HIGH VOLTAGE CAPACITOR DISHCARGE TYPE CUT (A.G)
            A 115 A.C is provided bu E.S.I. but to the primary coil of the transformer A to reduce the noise level a filter cut is provided at the primary 
            After paning 115V at the primary a seen way coil induces a voltage of about 2000V approximately which paner through solid rectifier A through resistance to the dual capacitor or storage capacitor which store the electrically charger
            In the next cycle a 20000 is paned through rectifier B this resistance

22. Combustion chamber used in a modern jet engines are
(a)    Can annular type
(b)   Annular type
(c)    Can type
(d)   As stated in 1 and 2

23. Exhaust nozzle is
(a)    No necessary for jet engines
(b)   Made up of titanium alloy
(c)    Made up of aluminum alloy
(d)   A must for jet engine

24. Internal energy of a perfect gas is
(a)    A function of temperature only
(b)   A function of pressure only
(c)    Always constant
(d)   A function of temperature and pressure

25. The turbo jet engines
(a)    Can be used in thermal power stations as prime stations as primer movers
(b)   Are more efficient at lower altitudes
(c)    Work on Newton’s third law of motion
(d)   (2) and (3) above are correct

26. Compression process in axial compressor is
(a)    Isothermal
(b)    Adiabatic
(c)    Isobaric
(d)   Isometric

27. Compressor pressure ratio of an engine compressor depends upon
(a)    Ambient pressure
(b)   Ambient temperature and ambient pressure
(c)    Speed and ambient pressure
(d)   Speed mass airflow and ambient temperature

The energy stored in a dual capacitor and storage charger at a fule charge level and then tenses the tube this caused charger when fully developed it induces in the primary winding of the transformer (TRIGGER), which is of up to app 2000 V
            This induces a appx of 20,000V to the secondary of the tram former winding and which gives high intensity current flow thr ignite plug which gives spark
            A bleeder resistance are provided for troiger capacitor to give protection for excess voltage
            Two igniter plug are used for capacitor discharge type cht for alternate operations
 
28. The fuel nozzles used in modern gas turbine engines
(a)    Are always of dual type
(b)   Are identical for engine with same power rating
(c)    Are welded to the combustion chamber
(d)   Is the last component in the fuel system

29. Anti – icing system used on jet aircrafts
(a)    Is fully automatic
(b)   Is to be used only to melt the ice formed
(c)    Never makes use of electrical heaters
(d)   Need not be used thought the flight

30. How many igniters are usually used on a turbine engine having nine burner cans?
(a)    One
(b)   Two
(c)    Three
(d)   Nine

31. The material used for jet engine is following main fine types
(a)    Titanium
(b)   Aluminum or Aluminum alloy
(c)    Nickel bare alloy
(d)   Nickel chrome alloy
(e)    Steel or stainless steel

 Titanium are high resistant to 1000 & corrosion and are used for fan blades and sometime for compressor vanes

Aluminum or aluminum alloy are used for jet engine for its light weight characteristics it is high resistant to corrosion heat

Nickel- chrome alloy’s re used fore turbine blades, which stands for high temperature

Steel or stainless steel alloy are used for rota vane or staten vane in an axial flow type jet

32. In an axial flow turbine engine, compressor bled air is sometimes used to aid in the cooling of
(a)    Oil
(b)   IGV
(c)    Fuel cooler
(d)   Turbine

33. Which of the following turbine fuel filters has the greatest filtering action?
(a)    Micron
(b)   Wire mesh
(c)    Wafer screen
(d)   Stacked charcoal

34. For starting a turbine engine
(a)    D.C motor is never used
(b)   Very very low cranking speeds are required
(c)    Ignition is necessary
(d)   Statements 2 and 3 are correct

35. Mechanical integrity of the turbine as well as engine operating conditions of the engine can be checked by
(a)    Engine oil pressure
(b)   Exhaust gas temperature
(c)    Engine oil temperature
(d)   Engine pressure ratio

36. Which parameter will determine engine power?
(a)    EGT and vibration meter
(b)   RPM and oil pressure
(c)    RPM and fuel pressure
(d)   EPR OR RPM

37. Mark the correct statement
(a)    Thrust reverse reduces landing roll
(b)   Oil pressure for jet engine is always regulated
(c)    VSV’ are not provided on modern jet engine
(d)   By providing fire wall in the engine cowl compartment engine fire detection element can be eliminated