Gas Turbine Flashcards by Alex Bates

What is working fluid

Any gas or liquid that can do work by expansion or flow or compression

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What is a turbine

A bladed spool designed to rotate, when working fluid acts on it

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Define what a compressor is

A bladed spool designed to do work on a fluid when it is rotated

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Function of a gas turbine

Convert heat energy into rotary motion

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Type 45 propulsion configuration (iep)

Integrated electric propulsion

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Type 23 propulsion configuration CODLAG

Combination of diesel electric and gas

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Positives is gas turbine

Quick start 
High power to weight 
Low maintenance 
Low man power 
Remotely controlled

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Air intake filters stages ?

1-spray eliminator
2-knit mesh filter
3-water Separation

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What does the spitter silencer do

Straighten out air flow and reduce air noise

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What does the stone guard do

Prevents large particles entertaining the turbine

Usually in maintenance periods

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What are transition ducts

Provides smooth change from square cross section to circle for gas turbine

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What do cascade bends do

Smoothly direct air through a 90 degree turn

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What is the engine intake flare

A seal which connects the gas turbine to the air intake

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What can the water wash ring do

It has holes to allow water into the gas turbine to clean the turbines

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What is the purpose of smoothing air Flow

To emotive efficiency of the gas turbine

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What are the two purposes of the module ventilation system

Get rid of oxygen supply in even of a fire

To allow air flow to cool gas turbine

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What theorem is used to creat air flow

Bernoullis theorem

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What is Bernoullis theorem

As a substance velocity increases the pressure decreases

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Explain the module ventilation system

Air drawn in, due to the a depression formed at the other end.
air circulates around module
rushing exhaust gasses create depression, making flow in the system

Five stages of a gas turbine

Induction 
Compression 
Combustion 
Power
Exhaust

3 times of air in power chamber

Primary air
Secondary air
Tertiary air

What compression rate will the compressors change the air to

19:1

Role of the primary air

All used for combustion

Role Of secondary air

Ensure complete combustion

Provides a layer of air between can and fire to prevent over hearting

Role of tertiary air

Becomes working fluid (used for thrust)

What is the use of the LP and HP turbines

They drive a shaft due to the thrust produced and turn the compressors. - LP solid shaft - HP hallow shaft - 1/3 of the energy produced used for this

What does the power turbine do

The thrust drives a turbine on a shaft, which will drive a generator or the gearbox -2/3 of the energy produced used for this

What lub do the navy use

OX22

What do mag chips do

Early failure detections | By ferrous debris sticking to it, indicating An issue

How often are magchips checked

Everyone 24 hours | Never wipe of particles

Safety devices on gas turbine

- Hand trip - fire detectors - power turbine entry temperature - partial over speed - lp/hp governors - vibration monitors - power turbine over speed - safety interlocks

Explain partial over speed

If propeller comes out the water this will limit fuel to the engine to prevent over speed

What are the LP/HP governors

Controls speed of the compressors

What does the Power turbine over speed do

If the turbine exceeds 110% of max speed engine shuts of

Two hazards

Igniters abs noise

How long must you leave the igniters

5 minutes

When can you enter the engine module

Only at idle Permission of meo Ear defenders most be worn

How do we put out fire in the module

Bcf or btm drench system - Always armed if engine running - always disarmed if someone in module

Hourly checks when watch keeping

Pressure and temperature Oil level Noises Leaks

Explain how a wet motor cycle is done

1The start motor is used to spin the engine -Fuel supply is on but igniters are turned of -

When is a wet motor cycle done

- Prove the fuel system after maintenance | - bleed any air from fuel system

Explain a dry motor cycle

Engine turned by start motor Fuel is of Igniters are of

Why is a dry motor cycle done

Purge fuel and water from combustion chamber - After a failed motor start - After a wet motor cycle - To enable water washing

Why do we do water washing

Clean turbines for efficacy | And compressor blades

What is inhibiting

A process carried out when ship is along side for a long period. PX24 Sprayed in engine to prevent corrosion