Gas Turbines Flashcards
What does CODLAG Stand for?
Combination of Diesel Electricity and Gas
What type of gas Turbine is on a T23?
2 x Spey Gas Turbines
Advantages of Gas Turbines?
Allow the ship to get underway quickly.
Ease of operation due to Remote Control.
High Power to Weight Ratio.
Min Ship-Borne Maintenance.
Low man power requires.
Explain 3 stage air filter?
S1 - Spray eliminator:
Aluminum fins change the direction of airflow to remove water droplets.
S2 - Knitmesh Filter: Removes dirt particles
S3 - Water Seperation: Drains water into a trough, which ensure water tight seal across the bottom of filters. It’s kept at the perfect level by a manometric bend.
Explain Splitter Silencer?
Splits air flow stream which will reduce air noise. This is achieved by passing air over aerofoil shaped veins.
Explain Transition duct:
Provides a smooth transition of airflow from square cross section to circular cross section.
Explain cascade bend:
Allows air to smoothly change flowing direction by 90° without creating turbulence.
Explain engine intake flare:
Seals the intake from the rest of the module and house the “water wash ring.” It is made of glass reinforced plastic.
Fully explain how the module ventilation system works.
The module ventilation flaps isolate the module if there is an emergency. When the engine is running, the module ventilation flaps are to be open to allow for airflow to cool the module and push out exhaust fumes.
The module is ventilated by: Bernoullis theory, the Venturi effect & Vent by Volute (VxV)
How are compressors driven?
When combustion takes place in the combustion cans, a portion of the air in the CC becomes the “Working Fluid.” This working fluid is used to drive the compressors.
What is the purpose of the power Turbine?
The power turbine uses 2/3 of the energy from the working fluid to drive the shaft connected to either a gearbox or a generator.
What are Mag Chips? Where are they fitted and how often are they checked?
Mag Chips are fitted for early failure detection. They are found in the oil return (scavenge leg) and collect ferrous debris. They are checked every 24 hours.
Which oil is used in a Spey Gas Turbine?
OX24
Name the safety features on Gas Turbines.
1) Hand Trip
2) Fire Detectors
3) Partial Overspeed
4) Power Turbine Overspeed
5) LH/HP Governors
6) Monitors
7) PTET - Power Turbine Entry Temperature
Explains Partial overspeed trip.
If the rotation of the propeller changes, for instance, if it comes out of the water, this will reduce this amount of fuel to the engine to prevent the prop over speeding.
