Figure 2-19.--Gas turbine module cooling.
MODULE COOLING SYSTEMS
CG, DD, COOLING SYSTEM
Navy GTEs are not rated for operation in
In this system, main engine cooling air is
ambient temperatures above 130F. A module
extracted from the main intake duct at a point
cooling system must be used to prevent module
between the blow-in doors and the main duct
temperatures from exceeding 130F. The LM2500
silencers. It is then ducted to the engine enclosure.
GTE module uses a combination of fan-forced
The cooling air duct contains a silencer and a
ventilating air and exhaust gas eduction to cool
cooling air fan (see fig. 2-12). The silencer has a
the GTM (fig. 2-19). The location and operation
double-walled cylinder. The cooling is activated
of the cooling fan system differ among ship
either manually or automatically from the PACC and
classes, but the ducting is connected to a flexible
the PLCC (automatically from the Shaft Control Unit
joint common to all enclosures. Cooling air is
(SCU) on the DDG-51 class); the cooling system must be running
taken into the cooling duct and pressurized by
for engine operation.The space between is filled with sound-
the fan. It is then discharged at the electro-
deadening material. Suspended in the center of
pneumatically controlled ventilation damper on
the cylinder is a torpedo-shaped baffle. It is made
the top of the module. This vent damper also will
of perforated stainless steel sheet filled with
isolate the enclosure in case of fire or when the
sound-deadening material. The silencer forms a
engine is secured. Once the air enters the module,
section of the cooling air duct. The cooling air
fan is located in the duct between the engine
a natural swirling effect takes place around the
enclosure and the silencer. The fan is rated at 80
engine. The cooling air moves to the back of the
3
hp and 17,000 cubic feet per minute (ft /min) airflow.
module where it is removed by the exhaust
eductor. A temperature monitor is located on the
From the cooling fan, the air is ducted to the
enclosure ceiling just forward of the exit area. This
engine enclosure. It enters the enclosure through
monitor provides an alarm indication to the
a ceiling-mounted vent damper. Then it circulates
control consoles if the enclosure temperature
around the engine. The air exits the enclosure
exceeds a set limit. Although the cooling systems
through the exhaust plenum. The cooling is
of the different class ships perform the same
activated either manually or automatically from
function, they are constructed differently. The
the PACC or the PLCC and must be running for
following sections of this chapter describe these
engine operation. The vent dampers are electro-
differences.
pneumatically operated. They use air from the
2-17
