Gas Turbines Flashcards
Learn about gas turbines
What does CODLAG stand for
Combination of diesel electric and gas
What are the turbines called and what ship are they on
There are 2 spey engines on the type 23
What are the advantages of a gas turbine
To get underway quickly Ease of operation with the emphasis on remote control High power/weight ratio Minimum shipboard maintenance Low manpower requirement
What does the 3 stage filtration do
Filters sea sprey and dirt
What does the stone guard do
Prevents large coarse particles of debris from entering
What are the 3 stages of a 3 stage filtration system
And what do they do
Sprey eliminator which removes water from the air
Knitmesh filter which removes particulate matter
Water seperation where water drains into a trough creating a water seal accross the bottom of the filters
What does a splitter/silencer do
Reduces air noise and buffering
What does the transition duct do
It turns the square trunking in to a round pipe smoothly
What does the cascade bend do
Directs the air smoothly at a 90 degree angle without causing turbulence
What does iep stand for
Intergrated electric propulsion
Explain how the module ventilation works
- The depression of air from rushing exhaust gases is created. Bernoulis principle
- Vent flaps remain open when running only shut to help extinguish a fire
- Air circulates around the module
- Air is drawn in because of the depression on the other end
What are the 5 phases of a gas turbine
Induction Compression Combustion Power Exhaust
What happens during the LP/HP compressors
Air is drawn in and gradually gets compressed as the gaps between the blades get smaller.
Compressed to 1/20
What happens during the combustion cans
Air is drawn in to aid the burning fuel and get heated up to create the working force
What do the HP/LP turbines do
They use the moving air (working force) to turn the LP/HP compressors
What is the purpose of the power turbine
The remaining energy of hot air passes through the turbine creating rotary force turning the shaft to gearbox
What are the 3 names and percentages of the air entering the combustion can
Primary air 15%
Secondary air 10%
Tertiary air 75%
Explain primary, secondary and tertiary air
Primary air helps atomise the fuel and provides air for the initial combustion
Secondary air ensures complete combustion and provides a layer of air between the fuel and flame tube
Tertiary air is heated up by the cobustion process causing rise in pressure and becomes the working fluid.
What needs lubricating in the gas turbines
Shaft bearings need lubricating using OX22 lubricating oil using a scavenge system with magnetic chip detectors
what is the function of the gas turbine
is to convert heat energy into rotary motion for ships propulsion
what is the purpose of the engine intake flair
seals the engine intake from the rest of the module and houses the water wash rings
what are the magnetic chip detector and how often are they checked
fitted into the scavenge system to collect ferrous debris, give an early indication of engine wear, checked every 24 hours of running time and the debris is not to be removed but to be measured and logged.
list the safety devises fitted to a gas turbine
power turbine overspeed safety interlocks hand trip fire detectors power turbine entry temperature partial overspeed safety LP/HP compressor governor vibration monitor
explain how the power turbine overspeed works
if speed reaches 110 percent of safe limit the high pressure shut off cock will stop the engine by isolating its fuel supply
