Q6-10.
What is the major difference between a
turboshaft and a turbofan engine?
Q6-11.
What is the heart of the gas turbine fuel
system?
Q6-12.
List some of the engine-operating variables
that are sensed by modern fuel controls.
Q6-13.
What are the two main parts of a turbine that
need lubrication?
Q6-14.
In most lubricating systems, a pressure pump
or system provides oil that lubricates and
cools. What system returns the oil to the tank
for reuse?
Q6-15.
What is the difference between low- and high-
voltage
capacitor
discharge
ignition
systems?
Q6-16.
Where is the accessory section of the gas
turbine engine usually mounted?
THE BRAYTON CYCLE
LEARNING OBJECTIVE: Recognize the
Brayton cycle and its application to gas turbine
and jet engines.
A cycle is a process that begins with certain
conditions and ends with those same conditions. The
Brayton Cycle is illustrated in figure 6-20. Note that in
the gas turbine engine, each cycle is not only performed
continuously, but also by a separate component
designed for its particular function.
Since all of the events are going on continuously,
we can say that all gas turbine engines work on an open
cycle. Figure 6-20 compares the cycles of operation of a
piston-type (reciprocating) engine and a gas turbine
engine. The piston-type engine produces power by
intermittent combustion. The gas turbine engine
produces power continuously.
Q6-17.
What is the Brayton cycle?
ENGINE IDENTIFICATION
LEARNING OBJECTIVE: Identify the two
engine
designation
systems
to
include
symbols, numbers, indicators, and special
designators.
Presently two engine designation systems identify
aircraft power plants. One system is described in Air
6-16
Figure 6-20.—A comparison of turbojet and reciprocating engine cycles.
