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Gas Turbines THeory 2 > Turbines > Flashcards

Turbines Flashcards

1
Q

When do igniters stop operating?

A

Once flame is established

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2
Q

What is the function of a gas turbine?

A

To convert heat energy into rotary motion for ship propulsion

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3
Q

In mechanical terms (component ‘a’ is bolted to component ‘b’ etc), where does the transmission system begin ?

A

At the power turbine

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4
Q

What lubricating oil is commonly used in RN gas turbines?

A

OX22

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5
Q

Name 5 trips and safety devices that you would find on a gas turbine.

A
  1. Fire detector
  2. Hand Trip
  3. Partial overspeed
  4. Vibration monitor
  5. LP/HP Governors
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6
Q

What is the largest ratio that can be sensibly achieved on single gear reduction?

A

15:1

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7
Q

How often are FL cut-ins carried out?

A

Every 24Hrs

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8
Q

What is the purpose of water washing?

A

To remove fowling deposits such as dust & carbon, from the compressor blades

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9
Q

In relation to the fuel system what is the max fill level for displaced tanks?

A

90%

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10
Q

In relation to the fuel system what is the max level for undisplaced tanks?

A

95%

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11
Q

In relation to the fuel system the Max interface for water reaction test as above?

A

2%

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12
Q

Name the components that are used to support the weight of the shaft, outside of the hull.

A
  • Intermediate A Bracket
  • Main A Bracket
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13
Q

Name the gas turbines used in the navy

A
  • Spey on type 23’s
  • WR21 on 45’s
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14
Q

What does IEP mean?

A

Integrated Electric Propulsion

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15
Q

What does CODLAG mean?

A

Combination of Diesel Electric and Gas

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16
Q

What are the 5 Advantages of Gas turbines?

A
  1. Get underway quickly
  2. Ease of operation (emphasis on remote control)
  3. High power/weight ratio
  4. Minimum shipboard maintenance
  5. Low manpower requirement
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17
Q

What is the purpose or air intake filters?

A

to Stop water, dirt and debris from the air entering the intake trunking.

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18
Q

What does the splitter/silencer do?

A
  • Smooths out airflow (removes turbulence)
  • reduces noise
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19
Q

What is a stone guard?

A

Its a wire mesh that prevents large particles of debris from entering turbine

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20
Q

What does the Transition duct do?

A

Turns square airflow into circular without creating turbulence

21
Q

What does the cascade bend do?

A

Directs the air smoothly through 90 degrees.

22
Q

What is the Engine intake flare?

A

It seals the engine intake from the rest of the module and houses the water wash ring.

23
Q

Name the 5 parts of the operating cycle of a Gas turbine.

ICCPE

A
  1. Induction
  2. Compression
  3. Combustion
  4. Power
  5. Exhaust
24
Q

What is Bernoulli’s principle?

A

pressure decreases when the flow speed increases

25
Q

What is a ‘Mag chip’ and what does it do?

A

they are small magnets, fitted to the oil system to collect debris.

they are inspected every 24hrs not to be cleaned, the debris is monitored

26
Q

After use igniters must not …..

A

Touched for at least 5 minutes to allow stored energy to be discharged

27
Q

What running checks are carried out hourly on a running engine?

A
  • Pressure & temperature
  • Oil levels
  • Noise & Vibration
  • Leaks
28
Q

What is Waterwashing?

A

The procedure used to remove deposits from the compressor blades

29
Q

What is PX24?

A

It is an inhibiting fluid, sprayed into the engine to remove moisture and protect the engine.

30
Q

What is partial overspeed used for?

A

It reduces speed if propeller comes out of water

31
Q

What do Governors do?

A

Control speed

32
Q

GAS TURBINE AIR FLOW

Describe Primary air..

A

15 %

For initial combustion

33
Q

Describe Secondary air..

A

10%

Ensures fuel is fully burnt

34
Q

Describe tertiary air…

A

75%

Heated by combustion process, becomes working air in the turbines

35
Q

Describe Igniter…

A

2000 Volts on initial starting then it is deenergized as it is no longer needed

36
Q

describe LP/HP Compressors..

A

LP comp is attached to LP turbine,

HP comp is attached to HP turbine

the shaft runs within a shaft and the turbines turn the compressors

37
Q

Describe the Induction process

A

Air gets drawn in, enters LP compressor which increases the pressure using rotating blades

38
Q

What is the 1st stage of a 3 stage filter?

A

Spray eliminator

Air gets drawn through a torturous path, which removes moisture.

39
Q

What is the 2nd stage of air filter?

A

Knitmesh

criss cross fabric that collects particles

40
Q

What is the 3rd stage of air filters?

A

another torturous path where all water is removed

41
Q

What is the manometric leg?

A

the water is collected in a trough at the bottom of the filters, where the water level is maintained by the manometric leg.

Stops unfiltered air entering system

42
Q

What is partial overspeed for?

A

Reduces speed if propeller comes out of water

43
Q

What is Power turbine over-speed?

A

if turbine speed reaches 110% the HPSOC (High pressure shut off cock)

will stop engine

44
Q

Describe wet motoring & when is it done?

A
  • Fuel on
  • Turn engine
  • fuse removed
  • ignitors off
  • After maintenance & vent air from system
45
Q

Describe Dry motoring & when is it done?

A
  • Turn engine over
  • No fuel
  • No ignitors
  • After wet motoring, after combustion to get rid unburnt fuel & so washing routines can be done
46
Q

Describe Water washing & when is it done?

A
  • WR21 150 running hours
  • Spey 100 hours or 2 months
  • When performance deteriorates
  • Removes fouling from compressor blades
  • Done after cooling period of 30 mins
47
Q

What is inhibiting done for?

A

to protect engine from corrosion if it is shut down for a period of time.

PX24

48
Q

What are the 4 Inhibiting warnings?

A
  • PX24 is flammable
  • no smoking
  • ensure engine room vents are running
  • ensure engine ignitors are removed

Gas Turbines THeory 2 (4 decks)

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