Turbines

Question 1

When do igniters stop operating?

Answer 1

Once flame is established

Question 2

What is the function of a gas turbine?

Answer 2

To convert heat energy into rotary motion for ship propulsion

Question 3

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

Answer 3

At the power turbine

Question 4

What lubricating oil is commonly used in RN gas turbines?

Answer 4

OX22

Question 5

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

Answer 5

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

Question 6

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

Answer 6

15:1

Question 7

How often are FL cut-ins carried out?

Answer 7

Every 24Hrs

Question 8

What is the purpose of water washing?

Answer 8

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

Question 9

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

Answer 9

90%

Question 10

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

Answer 10

95%

Question 11

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

Answer 11

2%

Question 12

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

Answer 12

• Intermediate A Bracket
• Main A Bracket

Question 13

Name the gas turbines used in the navy

Answer 13

• Spey on type 23’s
• WR21 on 45’s

Question 14

What does IEP mean?

Answer 14

Integrated Electric Propulsion

Question 15

What does CODLAG mean?

Answer 15

Combination of Diesel Electric and Gas

Question 16

What are the 5 Advantages of Gas turbines?

Answer 16

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

Question 17

What is the purpose or air intake filters?

Answer 17

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

Question 18

What does the splitter/silencer do?

Answer 18

• Smooths out airflow (removes turbulence)
• reduces noise

Question 19

What is a stone guard?

Answer 19

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

Question 20

What does the Transition duct do?

Answer 20

Turns square airflow into circular without creating turbulence

Question 21

What does the cascade bend do?

Answer 21

Directs the air smoothly through 90 degrees.

Question 22

What is the Engine intake flare?

Answer 22

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

Question 23

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

ICCPE

Answer 23

1. Induction
2. Compression
3. Combustion
4. Power
5. Exhaust

Question 24

What is Bernoulli’s principle?

Answer 24

pressure decreases when the flow speed increases

Question 25

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

Answer 25

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

Question 26

After use igniters must not …..

Answer 26

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

Question 27

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

Answer 27

* Pressure & temperature * Oil levels * Noise & Vibration * Leaks

Question 28

What is Waterwashing?

Answer 28

The procedure used to remove deposits from the compressor blades

Question 29

What is PX24?

Answer 29

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

Question 30

What is partial overspeed used for?

Answer 30

It reduces speed if propeller comes out of water

Question 31

What do Governors do?

Answer 31

Control speed

Question 32

**GAS TURBINE AIR FLOW** Describe Primary air..

Answer 32

15 % For initial combustion

Question 33

Describe Secondary air..

Answer 33

10% Ensures fuel is fully burnt

Question 34

Describe tertiary air…

Answer 34

75% Heated by combustion process, becomes working air in the turbines

Question 35

Describe Igniter…

Answer 35

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

Question 36

describe LP/HP Compressors..

Answer 36

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

Question 37

Describe the Induction process

Answer 37

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

Question 38

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

Answer 38

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

Question 39

What is the **_2nd_** stage of air filter?

Answer 39

Knitmesh criss cross fabric that collects particles

Question 40

What is the 3rd stage of air filters?

Answer 40

another torturous path where all water is removed

Question 41

What is the manometric leg?

Answer 41

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

Question 42

What is partial overspeed for?

Answer 42

Reduces speed if propeller comes out of water

Question 43

What is Power turbine over-speed?

Answer 43

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

Question 44

Describe **_wet motoring_** & when is it done?

Answer 44

* Fuel on * Turn engine * fuse removed * ignitors off * After maintenance & vent air from system

Question 45

Describe **_Dry motoring_** & when is it done?

Answer 45

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

Question 46

Describe **_Water washing_** & when is it done?

Answer 46

* 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

Question 47

What is **inhibiting** done for?

Answer 47

to protect engine from corrosion if it is shut down for a period of time. PX24

Question 48

What are the 4 Inhibiting warnings?

Answer 48

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