combustion chamber 3/5
DESCRIPTION
TRANSCRIPT
Ignition Ignition & & Fuel SupplyFuel Supply
*** Some gas turbines are “bi-fuel”. They may burn a mixture of gas and liquid fuel.
Ignition occurs during the start cycle
FUEL is injected at the upstream end of the
burner.
Intro Process Fuel supplyTypes Materials
Intro Process Fuel supplyTypes Materials AE 424AE 424COMBUSTION CHAMBERCOMBUSTION CHAMBER
The igniter plug(s) is (are) located
in the combustion liner adjacent
to the start fuel nozzle.
TWO is a typical number
The flame lights off the can closest the igniter
and cross tubes rapidly conduct the flame
to the other combustion cans.
Intro Process Fuel supplyTypes Materials
Intro Process Fuel supplyTypes Materials AE 424AE 424COMBUSTION CHAMBERCOMBUSTION CHAMBER
On engine shutdown, or, if start failure occurs,
the combustion chamber drain pressure-actuated valve
automatically DRAINS any raw fuel from the
combustion chamber
Intro Process Fuel supplyTypes Materials
Intro Process Fuel supplyTypes Materials AE 424AE 424COMBUSTION CHAMBERCOMBUSTION CHAMBER
Fuel NozzlesFuel must be atomised or
vaporised
Function: inject the fuel into the combustion chamber
Intro Process Fuel supplyTypes Materials
Intro Process Fuel supplyTypes Materials AE 424AE 424COMBUSTION CHAMBERCOMBUSTION CHAMBER
Common Types
•Vaporiser •Atomiser
Intro Process Fuel supplyTypes Materials
Intro Process Fuel supplyTypes Materials AE 424AE 424COMBUSTION CHAMBERCOMBUSTION CHAMBER
VAPORISER TYPE
Intro Process Fuel supplyTypes Materials
Intro Process Fuel supplyTypes Materials AE 424AE 424COMBUSTION CHAMBERCOMBUSTION CHAMBER
ATOMISING TYPE
Swirl Atomiser
• consists of a small cylindrical or conical cavity into which a number of streams of fuel enter through tangential holes.
• The direction of fuel entry into the cavity creates a vortex and the swirling fuel leaves in atomised form from a single orifice.
Intro Process Fuel supplyTypes Materials
Intro Process Fuel supplyTypes Materials AE 424AE 424COMBUSTION CHAMBERCOMBUSTION CHAMBER
SIMPLEX
provides good atomisation at HIGH fuel pressures
• unsatisfactory at LOW fuel pressures and at LOW engine
rpm, especially at high altitudes.
Intro Process Fuel supplyTypes Materials
Intro Process Fuel supplyTypes Materials AE 424AE 424COMBUSTION CHAMBERCOMBUSTION CHAMBER
DUPLE & DUPLEX
• two sets of atomisers, one for low flows and both combined for high flows
• two manifolds, the primary and the main,
supply fuel to the nozzles• each nozzle has two swirl chambers, one for the primary flow and the other
for the main flow
Intro Process Fuel supplyTypes Materials
Intro Process Fuel supplyTypes Materials AE 424AE 424COMBUSTION CHAMBERCOMBUSTION CHAMBER
Spill Type
• supply fuel to the swirl chamber at a high pressure all the time
• ADVANTAGE: satisfactory swirl providing constant and efficient fuel atomisation (even at the extremely low fuel flows that occur at high altitude)
Intro Process Fuel supplyTypes Materials
Intro Process Fuel supplyTypes Materials AE 424AE 424COMBUSTION CHAMBERCOMBUSTION CHAMBER
Rotary Atomizer
• feeds fuel into the centre of the main shaft
• fuel is atomised by the CENTRIFUGAL action of the shaft.
Intro Process Fuel supplyTypes Materials
Intro Process Fuel supplyTypes Materials AE 424AE 424COMBUSTION CHAMBERCOMBUSTION CHAMBER
Spray Nozzle
Intro Process Fuel supplyTypes Materials
Intro Process Fuel supplyTypes Materials AE 424AE 424COMBUSTION CHAMBERCOMBUSTION CHAMBER
• Primary air is introduced with the injected fuel. Aerating the spray in
this manner achieves greater burning efficiency, therefore
reducing both carbon formation and exhaust smoke. The comparatively
low pressures required for atomisation also makes it possible to
use the lighter gear-type pump.
Intro Process Fuel supplyTypes Materials
Intro Process Fuel supplyTypes Materials AE 424AE 424COMBUSTION CHAMBERCOMBUSTION CHAMBER