Combustion Flashcards
What’s the purpose of a combustion chamber
Produce stream of hot gas by the continuous combustion of a fuel air mixture
What are requirements of the combustion chamber
Small and light to save weight
a dependable cooling system
a high operating lifetime
Combustion needs to occur with a minimum of what
Minimum of pressure loss
Main component of combustion chamber
Casing and flame tube which is inside casing
What is the chamber casing
Outer shield of combustion section which takes pressure loads
What does the casing housing support
Supports flame tube and other combustion components
Conditions for combustion
Correct air to fuel ratio
air velocity slow enough to make sure combustion is complete
How is fuel and air mix ignited
Electrically by igniter plug
When does the ignition turn off
Once combustion has started
Kerosene air ratio
15:1 air to fuel
2 different airflows in compressor
Primary and secondary
How much primary air is used for combustion
20-30% of airflow
What zone does the flame stabalise
Primary zone
Centre flame temperature
2000 degrees C
What’s the secondary airflow used for
Cooling as combustion chamber components can melt
How does secondary air enter dilution zone
By dilution air holes
3 types of combustion chamber
Can
Can-annular
Annular
Most popular chamber used
Annular
Disadvantage of annular
Maintenance and manufacturing costs
Advantage of annular
Good efficiency and high service life
What does the flame tube do
Stabilisers , controls and guides flame during combustion
What does the combustion case do
Carries structural loads between compressor case and turbine case and houses flame tube
What is external components of combustion section
Fuel nozzle & igniter plug
Combustion case assembly parts
Outer wall
Inner wall
A diffuser
What does a diffuser do
Slows air with a divergent duct
What are exit guide vanes
Stator vanes at the last stage of the HPC
What’s the parts of the flame tube assembly
Outer & inner liner
Outer & inner cowl
Dome
What does the dome connect
Connects inner and outer liner
How is the flame tube and fuel nozzle connected
Bolted to combustion case structure
What is two piece flame tube
Outer liner and dome flame tube made is one piece
Where is the dome in a two piece flame tube
Centred in combustion case by mounting pins
How is the inner liner different in a two piece flame tube
Bolted to inner flange of HPT nozzle guide vanes
What vanes does primary airflow enter flame tube through
Swirl vanes
How does secondary airflow enters flame tube
Passes cowl and enters through liners
How does secondary airflow cool the flame tube
Forms cooling film on inner surface which protects liner from intense heat
What is the use of a cooling film process called
Film cooling
What are the 3 methods of film cooling
Machine
Splash
Corrugated strips
I’m transportation cooling method what are flame tube liners covered with
detachable tiles called liner segments
What’s a benefit of transpiration cooling method
Requires less air for cooling the flame tube
