GT Flashcards
Describe Primary air
- 15% of the total air
- It is the air used for intial combustion and helps atomise the fuel
Describe Secondary air
- 10% of the total airflow
- It ensures that all fuel has been burnt
- and provides a layer of air between the fuel and flame tube ,preventing flame impingement
Describe Tertiary air
- The remaining 75% of air
- heated up by thecombustion process and is the working fluid in the GT
Describe GT fuel injector (Burner)
Injects atomised fuel into the combustion chamber in a fine mist meaning the fuel more efficiently mixes with the air
Describe GT ingniter
- Produces 2000V spark that ignites atomised fuel, starting the engine
- De-energises once engine is running
Describe LP Compressor (GT)
- The first part air goes through in the GT
- Rotating blades compress the air as it is drawn through the rotating blades
- It is an axial flow pump
Describe HP Compressor (GT)
- Rotating blades slow down the air to increase it’s pressure again by a ratio of 19:1
Describe Combustion Chamber
- Where the atomised fuel and compressed air. is ingnited
- Most air entering the combstion chamber is used to cool the chamber,then is burnt further down once flame has been established.
- Designed to give maximum power in the smallest space with minimum losses
Describe LP & HP Turbines
- Hot gases leave the combustion chamber and drive the turbines
- The turbines in turn drive the compressors, making the engine self sustaining
- Turbines are connected to the compressors by a shaft within a shaft
- 1/3 of the energy from combustion is lost at this stage
GT operate on what principle?
- Brayton cycle ( thermodynamics)
- It describes the operation of engines that have air or gas as thier working fluid
Describe Power turbine
The power turbine drives the input shaft of the gearbox,which drives the propeller shaft
Describe GT Lubrication system
- Oil is sent to the turbine & comp shaft by a gear wheel pump
- It is called a scavenge system
- It incorperates mag chips that collect ferrous metal from the GT
- Checked every 24hrs for debris
What is flame impingment?
when a flame actually touches or engulfs the tubes causing hot spots
What is an axial flow pump?
common type of pump consists of a propeller (an axial impeller) in a pipe
Why does air heat when compressed?
When in a big open space, they don’t hit each other very often. Up in the higher atmosphere, where the air is thin, they barely do, so it’s very cold. But when you compress air, the molecules are forced into closer quarters. They colide and interact with each other more and more, increasing the heat
