CHAPTER 12
GAS TURBINE COMPRESSORS
INTRODUCTION
FUEL
SPARK PLUG
IGNITOR
Gas turbines are a familiar sight on the flight decks
AIR IN
of aircraft carriers and the flight lines of naval air
stations. They are most often tractor mounted aboard
ship and trailer mounted at shore commands. The
primary use of gas turbine engines is to provide
TURBINE
pneumatic power to start aircraft engines. The
p n e u m a t i c b l e e d - a i r p ow e r i s h i g h - vo l u m e ,
COMPRESSOR
low-pressure compressed air, which is used to operate
equipment that requires a high volume of air. This
NOZZLE
includes aircraft engine starter motors,
COMBUSTION CHAMBER
air-conditioning systems, and aircraft generator test
stands.
FUEL
As an AS, you are required to maintain and repair
gas turbine engines used in support equipment. The
prolonged life and operational readiness of the gas
turbine engine invariably depend upon the familiarity
maintenance personnel have with the equipment.
It is essential that you know the engine as
thoroughly as possible. You should know what it is
designed to do and how it fulfills that function. You
should also be familiar with normal operating details
of the engine, such as oil pressures, temperatures, fuel
pressures, flows, consumption, and exhaust gas
temperatures. You should be familiar with all of these
COMPRESSOR - CENTRIFUGAL - FLOW
(DOUBLE - ENTRY TYPE)
operating conditions from starting to idle, from idle to
ASf12001
load, and from load to shutdown of the engine.
Figure 12-1.--Centrifugal-flow type engine.
DESCRIPTION AND PURPOSE OF GAS
advantages of the centrifugal type over the axial-flow
TURBINE ENGINES
type are as follows:
Simplicity of design and manufacture, thus
LEARNING OBJECTIVE: Identify the two
lower cost
types of gas turbine compressor engines.
Identify their various components.
Lighter weight
Basically, there are two types of gas turbine
Low starting power requirements
engines--the centrifugal-flow type and the axial-flow
type. (See figures 12-1 and 12-2.) By studying these
B e c a u s e t h e c e n t r i f u g a l - f l ow i s t h e m o s t
figures, you can see that the greatest single difference
commonly used in support equipment, the axial-flow
is in the compressor section. The construction features
will not be discussed. However, by understanding the
of the compressor (axial-flow or centrifugal-flow)
centrifugal-flow type, the axial-flow type can also be
determine the designation of the engine.
understood, since all other sections and components
except the compressor are very similar in design and
The centrifugal-flow compressor engine is the
most common engine used in support equipment. The
operation.
12-1
