The discussion in this paragraph describes briefly the airflow
through the engines and the operation of the Lycoming T53. The
capital letters in parentheses such as (A), (B), (C) and so on in the
discussion correspond to similar letters in figure 4.2 and refer you
to that particular portion of the engine diagram.
a. Air flow. Atmospheric air (A) is drawn into the annular
air passageway of the inlet housing (B) and passes rearward across
the variable inlet guide vanes (C). The vanes direct the air into
the engine compressor section. The air passageway in the compressor
section contains Eve rotating axial compressor stages with five sets
of stationary stator vanes, a set of exit guide vanes (D), and one
centrifugal compressor (E). As the air passes through this section,
each rotating axial compressor stage increases the pressure. The
exit guide vanes guide the air onto the centrifugal compressor which
further accelerates the air as it passes radially into the diffuser
housing air passageway (F). Vanes in the diffuser air passageway
convert the high velocity of the air into pressure and also change
the radial airflow to a rearward flowing direction.
At this point the air enters the combustor section,
passing around and into the annular combustion area (G) through
slots, louvers, holes, and scoops fabricated in the combustion liner.
On entering the combustion area, flow direction is reversed while
both air velocity and pressure drop. The air, at the same time,
performs the multiple functions of cooling the combustor liner;
mixing with fuel, and burning, sustaining, and maintaining the high
heat combustion within a confined area; and absorbing the heat of
combustion so as to lower the heat to a usable temperature.
Combustion is made possible by introducing fuel into the combustion
area through 22 atomizers. The atomized fuel mixes with the air,
burns, and produces temperatures as high as 3,500 degrees F.
As previously stated, this exceedingly hot gas is cooled
as it flows forward in the combustion area to the deflector, which
reverses the hot gas flow. Now flowing rearward, the gas is directed
across the twostage gas producer nozzle turbine system. The first
stage nozzle (H) directs the high energy gas onto the first stage
turbine (I), across the second stage nozzle (J) onto the second stage
turbine (K). The power system also uses the twostage nozzle turbine
concept. Therefore, on leaving the second stage gas producer
turbine, the gas, still possessing a high work potential, flows
across the third stage nozzle (L) onto the third stage turbine (M),
across the fourth stage nozzle (N) onto the fourth stage turbine (O).
On passing from the fourth stage turbine, the gas is exhausted into
the atmosphere through the exhaust diffuser passageway (P).