COMBUSTION SECTION
The combustion area consists of an annular re-
verse-flow combustion chamber enclosed in a
plenum, twelve duplex fuel atomizers (fuel
nozzles) and two igniter plugs. Two 180 de-
gree directional changes in the airflow pattern
take place through the combustor section. The
compressed air then passes through holes and
louvers designed to direct the flow and to keep
the flame pattern centered within the com-
bustor.
Each of the duplex fuel nozzles sprays fuel in
two distinct patterns, resulting in efficient,
controlled combustion. The mixture is ini-
tially ignited by the two igniter plugs, then be-
comes self-sustaining.
The combustion section controls the mixing
of fuel and air, contains the combustion of ex-
panding gases, and directs them to the tur-
bine section (Figure 7-2).
Two drain valves are located at the lowest part
of the combustion plenum and are used to
drain fuel from the engine following shut-
down or an aborted start.
TURBINE SECTION
The expanding combustion gases, generating
extremely high pressures as they exit the com-
bustion section are then directed to the turbine
section. The turbine section consists of four
axial-flow turbines (one HP and three LP).
See Figure 7-2.
L E A R J E T 4 5
P I L O T T R A I N I N G M A N U A L
7-4
FOR TRAINING PURPOSES ONLY
FlightSafety
international
LP
FOUR-STAGE AXIAL
COMPRESSOR
HP
CENTRIFUGAL
COMPRESSOR
HP
SINGLE-STAGE
TURBINE
BYPASS AIR
TURBINE
AIR
TOTAL AIR
INTO
ENGINE
FAN
ACCESSORY
GEARBOX
TRANSFER GEARBOX
COMBUSTION
LP
THREE-STAGE
TURBINE
Figure 7-2. Airflow Diagram