Gas Turbines Flashcards
What does IEP stand for?
Integrated Electric propulsion
What does CODLAG stand for?
Combination of diesel, electric and gas
What is the turbine used on a type 23
Spey
5 advantages of gas turbines
- Quicker to get underway
- More efficient
- Less maintenance
- Less manpower
- High weight to power ratio
What is the splitter/silencer
It makes the gas turbine quieter by absorbing the sound and creates less turbulence when the air passes through it
What does the stone guard do
The stone guard stops large debris from entering the module during maintenance
What is the transition duct
The transition duct changes the airflow from a square cross sectional airflow to a circular cross sectional air flow
What does the cascade bend do
This changes the airflow to a 90’ angle without causing any turbulence
What does the engine intake flare do
Seals the engine intake from the module and houses the wash rings
What does the manometric leg do
It maintains the water level and allows excess water to drain away
What are the 4 stages of the module ventilation
- Air is drawn in due to depression formed at the other end
- Air circulates keeping it cool
- Vent flaps must remain open
- The depression of air is formed by the rushing exhaust gases (Bernoulli’s Theorem)
What is the 5 stroke cycle of a gas turbine
- Induction
- Compression
- Combustion
- Power
- Exhaust
What are the safety devices for a gas turbine
- Hand trip
- Fire Detectors
- Partial overspeed safety device
- Vibration Monitor
What oil is used on a gas turbine
OX22
What is partial over speed
When the engine overspeed’s the propeller comes out of the water reducing the amount of fuel supplied and therefore reducing the speed
What is power turbine overspeed
If the power turbine reaches 110% of its safe limit the HP shut off cock stops the engine by isolating the fuel
What are the hazards with gas turbines
- igniters
- noise
What is wet motoring and when would it be performed
Turning over of the engine, fuel being supplied to the combustion chamber but the igniters are isolated and fuses removed
Would be carried out after maintenance
When would dry motoring be performed
To purge the combustion chamber of unburnt fuel
After wet motoring
To enable the compressors to be washed and maintained
