Gas Turbines

Question 1

What is the function of a Gas Turbine on board?

Answer 1

To convert heat energy to rotary motion for ship’s propulsion

Question 2

What is IEP

Answer 2

Integrated Electric Propulsion

Question 3

What is CODLAG

Answer 3

Combination of Diesel, Electric and Gas

Question 4

What are the advantages of Gas Turbines?

Answer 4

Ability to get underway quickly
High power/weight ratio
Minimum shipboard maintenance
Low manpower requirement

Question 5

Describe the 3-stage air filter system

Answer 5

1st stage - SPRAY ELIMINATOR- air changes direction because of the baffle plates, this causes water held in suspension to drop and fall to the water trough
2nd Stage- KNITMESH FILTER- air passes through this filter removing any particulate matter
3rrd stage- water drains into a water trough, any excess water drains away by the manometric leg which maintains the water level, a water seal across the bottom of the filter prevent unfiltered air from getting through

Question 6

What is the function of the Splitter/Silencer?

Answer 6

Smooths out the airflow removing turbulence, air noise and buffeting

Question 7

What is the purpose of the stone guard?

Answer 7

Prevents large particles of debris from entering the gas turbine during maintenance

Question 8

What is the function of the Cascade bend?

Answer 8

Lets the air travel through smoothly at a 90 -degree bend

Question 9

What is the purpose of the engine intake flare?

Answer 9

houses the water wash rings and seals of the engine intake from the rest of the module

Question 10

Describe the module Ventilation System

Answer 10

Air is drawn into the module caused by the depression formed at the other end
Air circulates the module keeping it cool
A depression of air is formed by the rushing of exhaust gasses (bernoulli's principle)

Question 11

What component provides drive into the gear box?

Answer 11

power turbine

Question 12

Explain how the compressors are driven

Question 13

Explain the air flow through a gas turbine

Question 14

What oil is used to lubricate a gas turbine?

Answer 14

OX22 lub oil

Question 15

Why are Mag Chips fitted and how often are they checked?

Answer 15

For early failure detection, they are inspected every 24 -running hour

Question 16

list the safety devices fitted to a gas turbine

Answer 16

hand trip 
fire detectors 
partial over speed 
low pressure and high pressure governors
safety interlocks 
vibration monitors

Question 17

Describe partial over speed

Answer 17

If the propeller comes out of the water, this reduces the amount of fuel to the engine preventing it from over speeding

Question 18

Describe power turbine over speed

Answer 18

if the power turbine exceeds 110% maximum speed the engine will shut down

Question 19

what hazards are associated with igniters

Answer 19

electric shock as it can produce volts up to 2000

Question 20

what hazards are associated with gas turbines

Answer 20

noise - it can get very loud

Question 21

whose permission is needed to enter a gas turbine module?

Answer 21

MEO- Marine Engineering Officer

Question 22

What firefighting systems are fitted to a gas turbine module?

Answer 22

the drenching sytem

Question 23

what are the dangers of module fire suspension systems?

Answer 23

it is very toxic

Question 24

What running checks are carried out on a gas turbine?

Answer 24

Pressure & Temperature, oil levels, noise and vibration, leaks

Question 25

what is a wet motor and when would it be performed?

Answer 25

wet motoring is turning over an engine using the starter motor and the fuel on that us supplied to the combustion cans
it is performed after maintenance

Question 26

what is dry motor and when can it be performed?

Answer 26

turning over the engine using the starter motor and the fuel and igniters are isolated

Question 27

how often is water washing performed?

Answer 27

for a WR21 150 running hours
Spey 100 hours or 2 months
or
when the engine deteriorates

Question 28

Draw and label a gas turbine intake system

Question 29

draw and label a module ventilation system

Question 30

draw and label a gas turbine engine

Question 31

draw and label a combustion can