engine. One emergency inlet door is located
mounted in each intake plenum upstream of the
between the uptake space and each combustion
moisture separators. The temperature is displayed
and cooling air duct. If the moisture separators
on the PCC demand display and on an edgewise
start to ice or are partially blocked for any reason,
meter on the LOP. The temperature signal is
the emergency inlet doors will open, These open
used by the propulsion control system (PCS)
automatically to provide inlet air from the uptake
for gas turbine enclosure ventilation damper
space and permit continued limited power engine
logic. It is also used for automatic GTE power
correction when operating in programmed control.
operation. The doors are pneumatically operated,
electrically actuated, and automatically controlled
A differential pressure sensor measures the
pressure difference between the intake duct and
by differential pressure switches. Each combustion
air emergency inlet door opens automatically at
outside atmospheric pressure. If the differential
a differential pressure of 9.0 inches of water
(in. H2O). The cooling air emergency inlet doors
intake LP alarm is activated on the PCC in the
central control station (CCS). This parameter can
open automatically at 3.75 to 4.25 in. H2O differential
pressure. You can actuate each door manually
also be demand displayed on the PCC.
using the air solenoid override at the door
control panel. If a loss of air pressure occurs, you
can open or close the doors manually using a
wrench at the door assembly.
EXHAUST SYSTEMS
The exhaust system (see fig. 2-11) routes the
Anti-Icing System
engine exhaust gases to the atmosphere. It is
An anti-icing system uses bleed air from the
designed to prevent re-ingestion of exhaust gases
into the intakes and to minimize heating of
GTE. It is used to prevent the formation of ice
topside equipment. This system also minimizes the
in the intake system. Anti-icing nozzles are located
upstream and downstream of the moisture
sound and the heat sensing of the ship by hostile
separators.
vessels and aircraft. Re-ingestion of the exhaust
gases is prevented by having the exhaust stack
The system has a sensor located in the inlet
ducting and a signal conditioner. Icing conditions
higher than the air inlet ducts. Sound level is
reduced by exhaust duct wall insulation. On some
exist when the ambient air temperature is below
41F and humidity above 70 percent. The signal
ship classes a silencer is installed to assist in noise
conditioner transmits a signal to the anti-icing
reduction. The exhaust gas temperature is reduced
when the module cooling air combines with the
system when these conditions occur. This signal
hot engine gases as they leave the GTM. Exhaust
provides an alarm indication at the control
gas temperature may be further reduced by an IR
console and provides an enable signal for
suppression system.
initiation of the anti-icing system.
Bleed air from each GG is piped to its
The exhaust duct is attached to the base and
associated intake system for anti-icing purposes.
The piping to each intake system contains a
turbine. An inner deflector is bolted to the
turbine rear frame hub and protects the
250/38 psig regulating valve to reduce the bleed
high-speed flexible coupling shaft from the
air pressure. The bleed air supplied to the intake
exhaust gases. An outer cone is bolted to
system provides anti-icing air for the moisture
the turbine rear frame outer flange to direct
separators, the GG bellmouth, and the enclosure
exhaust gases smoothly into the duct. The
cooling fan. Bleed air also supplies the cooling
exhaust extension differs in construction between
air bypass damper and the enclosure cooling air
damper.
the FFG- and the CG-, and DD-class
ships, but serves the same purpose. On the
The anti-icing pressure regulating valve is
FFG-class ship the exhaust extension is bolted
actuated from either the PCC or the local
to the exhaust duct through which the engine
operating panel (LOP). Valve status indication is
gases enter the exhaust duct. It creates an
provided at both control stations.
eductor effect which allows for enclosure
ventilation air to exit through the space
Intake Monitoring and Control
between the extension and the flexible joint.
The primary exhaust flexible joint connects the
Outside air temperature is sensed by a
resistance temperature detector (RTD). It is
ship's ducting to the enclosure.
2-14
