BOMBARDIER Challenger 601-3A CL-600-2B16 Pilot Training Manual page 220

FAN SECTION
air to the compressor of the core engine and the
second path directs air into the fan bypass duct.
The fan functions to accelerate a large air mass
to a moderate velocity through the bypass duct
and contributes approximately 80% of the total
thrust developed by the CF34 engine.
Compressor
The high-pressure (HP) compressor is located
aft of the front frame. This single-spool axial
compressor has 14 stages with a pressure ratio
of 14:1.
The HP compressor supplies air for cooling,
bearing and seal pressurization, hot-point
cooling, and for combustion in the core engine.
In addition, it supplies bleed air for the air-
plane's pneumatic services.
A variable-geometry system automatically
controls the inlet guide vanes and five variable
stator vanes to maintain a safe surge margin
across the HP compressor. This helps prevent
compressor stall or surges when the engine is
operating in the low-power range or during
rapid acceleration or deceleration.
FRONT FRAME
POWER
TAKEOFF
ASSEMBLY
FAN
DRIVE
SHAFT
RADIAL
DRIVE
SHAFT
Figure 7-2. CF34 Engine Modules
FOR TRAINING PURPOSES ONLY
FlightSafety Canada
CL-600-2B16 PILOT TRAINING MANUAL
COMBUSTION
SECTION
COMPRESSOR
SECTION
FAN DRIVE
SHAFT
ACCESSORY
GEARBOX
The variable-geometry system is controlled by
the fuel control unit (FCU) as a function of HP
compressor rpm (N
ature (T ). The FCU includes a fuel tempera-
2
ture compensating system to maintain the
required variable-geometry accuracy through-
out the normal fuel temperature range. The
variable-geometry module in the FCU will di-
rect HP fuel to two variable-geometry actua-
tors to operate the inlet and stator vanes.
A feedback system relays the position of the
vanes to the FCU at all times. When the en-
gine is static and during steady-state operation
at lower power, the inlet guide vanes and the
variable stator vane are at a close position.
This restricts the airflow to the HP com-
pressor to an amount that will ensure smooth
and continuous stall-free flow through the
compressor. As compressor rpm increases
with the addition of power, the variable-geo-
metry system moves the inlet guide vanes and
the variable stator vanes to the open position,
allowing unrestricted airflow through the com-
pressor. The response of this system will en-
sure a safe surge margin for the compressor
throughout its operating envelope.
HIGH-PRESSURE
TURBINE SECTION
LOW-PRESSURE
TURBINE SECTION
) and core-inlet temper-
2
CL 601-3R 7-3
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