details of the liner. The liner consists of an
is divided by the proper holes. Louvers and slots
undivided circular shroud extending all the way
divide the main streams--primary and secondary
around the outside of the turbine shaft housing
air. The primary or combustion air is directed
(fig. 1-27). The chamber is constructed of one or
inside the liner at the front end, where it mixes
more baskets. If two or more chambers are used,
with the fuel and is burned. Secondary or cooling
they are placed one outside of the other in the
air passes between the outer casing and the liner
same radial plane. The double-annular chamber
and joins the combustion gases through larger
is shown in figure 1-27.
holes toward the rear of the liner. Combustion
gases are cooled from about 3,500F to about
The combustion chamber housing is made in
1,500F forward of the turbine. Holes are
three sections. These sections are the inlet, center,
provided to aid in atomization of the fuel. These
and rear sections.
holes are located around the fuel nozzle in the
The inlet section receives the air from the axial-
dome or inlet end of the liner. Louvers are also
flow compressor. This section is a diffuser. It
provided along the axial length of the liners to
slows the velocity of the air by providing a larger
direct a cooling layer of air along the inside wall
area just before the liner area, thus raising air
of the liner. This layer of air controls the flame
pressure. Also present is a coarse wire screen,
pattern by keeping it centered in the liner. This
whose function is to increase turbulence to aid in
air layer prevents the 3,000F temperatures of the
fuel atomization.
combusting gases from burning the liner walls.
The center section of the chamber housing
Figure 1-26 shows the flow of air through the
surrounds the liner, providing an outer wall for
louvers in the double-annular type of combustion
the axial path of the air. The center section
chambers.
provides the mounting pads for the installation
of fuel drain valves. The drain valves drain
Annular or Basket Type
residual or accumulated fuel out of the combus-
tion chamber after engine shutdown. This action
The annular combustion chamber, the type
p r e v e n t s afterfires or excessive starting
usually found in axial-flow engines, consists
temperatures during the next start. Located on the
basically of a housing and a liner, similar to the
bottom of the housing are the spring-loaded
can type. The difference lies in the construction
combustion chamber drain valves. These valves
drain automatically whenever internal chamber
pressures approach atmospheric pressure. This
fuel is drained to an overboard drain compart-
ment in the airframe.
The rear section converges to form a narrow
annulus. This type of construction speeds up
airflow before it enters the turbine section.
Fuel is introduced through a series of nozzles
at the upstream end of the liner. The fuel nozzles
are screwed into fuel manifolds, located within
two concentric fairings. If the chamber liner is of
double-annular construction, there are two fuel
manifolds. Only one manifold would be required
if it were of single-annular construction. The two
concentric fairings that support the fuel manifolds
also perform the function of dividing the entering
airflow into three concentric annular streams. The
outer stream is delivered to the space between the
combustion chamber liner and the chamber
housing. The middle stream is delivered to the
space between the inner and outer sections of the
liner. The inner stream is delivered to the space
between the liner and the rotor shaft housing. The
two concentric fairings are supported by radial
Figure 1-26.-Components and airflow of a double-annular
struts in the diffuser section.
combustion chamber.
1-20
