Engineering Notes: Gas Turbines, Propulsion, and Auxiliary Systems

Comprehensive vocabulary flashcards covering marine engineering systems including main gas turbines, main reduction gears, shafting, lube oil, fuel oil, CPP, bleed air, seawater, LP/HP air, GTGs, degaussing, refrigeration, A/C, potable water, RO, drainage, VCHT, and steering.

Gas Turbine Main (GTM)

A General Electric LM2500 marine propulsion engine capable of producing $26,250$ brake horsepower.

LM2500 Engine Configuration

A split shaft engine design consisting of a gas generator (GG) and a Power Turbine (PT).

Gas Generator (GG)

A major section of the LM2500 engine consisting of $5$ assemblies: Compressor, Combustor, High Pressure Turbine (HPT), Transfer Gear Box (TGB), and Accessory Gear Box (AGB).

Main Reduction Gear (MRG)

A gear rated at $51,500$ horsepower that reduces the rotating speed of the LM2500 and converts high speed, low torque input to low speed, high torque output for the shafting and propeller.

Double Helical Gear

A gear design in which gear teeth are machined in a "V" pattern to reduce noise and axial thrust.

Articulated Gear

A reduction gear arrangement where the first reduction gear is coupled to the second reduction pinion via a quill shaft and flexible coupling.

Locked Train

A gear configuration in which each first reduction pinion is locked between two reduction gears.

Main Thrust Bearing

A bearing located behind each MRG in separate spaces that absorbs axial thrust from the shaft and transmits it to the hull of the ship.

Synchronizing Self Shifting Clutch (SSS)

Fully automatic, freewheeling devices that connect the GTMs to the MRG power train and transmit torque through splines and gear teeth.

Stern Tube Seal (MX9 Crane Seal)

A seal at the point where the shaft exits the ship, equipped with an inflatable boot that can be inflated by ship's LP air or $\text{CO}_2$ bottles.

Lube Oil Storage and Conditioning Assembly (LOSCA)

An assembly containing a $40\text{ gallon}$ storage tank used to filter, cool, deaerate, and store MIL-23699 synthetic lube oil for the GTM.

Fuel Oil Service System

A system that supplies clean, filtered fuel to the four GTMs and three GTGs, using NAVAL DISTILLATE (NATO F-76) as its preferred fuel.

Lube Oil Filter Separator Purifier (LOFSP)

Equipment rated at $500\,\text{GHP}$ with $15\text{--}18\,\text{PSIG}$ back pressure used to purify MRG sumps, CRP sumps, L/O pump settling tanks, and L/O storage tanks.

Bleed Air System Functions (SPAM)

System using engine bleed air for START air, PRAIRIE air system, ANTI-ICING system, and MASKER air system.

Prairie Air System

A system that uses bleed air to reduce noise emitted from the ship's propellers.

Masker Air System

A system that uses bleed air to mask high frequency noises emitted by machinery in the main spaces.

Controllable Pitch Propeller (CPP) System

A system used to vary the angle of attack of propeller blades with a maximum pitch range of $-61\%$ astern to $+120\%$ ahead.

Hydraulic Oil Power Module (HOPM)

The heart of the CPP system that filters and divides hydraulic oil into control oil ($400\,\text{PSIG}$) and power oil ($500\text{--}800\,\text{PSIG}$).

Emergency Pitch Mode

A CPP operating mode used after a failure where the propeller is locked in the emergency ahead position ($>120\%$ pitch) and cannot be locked astern.

Seawater Service System (SWS)

A centralized cooling system utilizing $5$ pumps rated at $1450\,\text{GPM}$ at $35\,\text{PSI}$ to supply cooling water to main engineering equipment.

Low Pressure Air System (LP Air System)

A system subdivided into vital air, non-vital air, and electronic dry air, supplied by three RIX Model Star 200 compressors rated at $200\,\text{SCFM}$ at $125\,\text{PSIG}$.

LP Air Priority Valves

Two valves (one per engine room) that automatically close to secure non-vital air when vital header pressure drops to $85\,\text{PSIG}$.

High Pressure Air Compressor (HPAC)

A five-stage, swash plate reciprocating RIX Model 5R5-75A compressor rated at $22\,\text{CFH}$ at $3000\,\text{PSIG}$.

Model AG9140 Gas Turbine Generator Set

An ALLISON 501-K34 single shaft generator set producing $2500\,\text{KW}$ of electrical power at $450\,\text{VAC}$, $4009\,\text{A}$, $3\,\text{phase}$, $60\,\text{Hz}$.

FI-QI Coil

An automatic degaussing coil that compensates for the longitudinal component of the ship's induced magnetic field.

A-Coil

An automatic degaussing coil extending athwartships that counteracts the athwartships component of the ship's induced magnetic field.

M-Coil

A manually adjusted degaussing coil that counteracts the vertical components (both induced and permanent) of the ship's magnetic field.

FP-QP Coil

A manually controlled degaussing coil in a figure 8 pattern that counteracts the permanent longitudinal component of the ship's magnetic field.

Refrigeration Plant

A system of two $1.5\,\text{ton}$ Carrier reciprocating R-134A units maintaining a chill room at $34\text{--}36^\circ\text{F}$ and a freeze room at $0\text{--}(-8)^\circ\text{F}$.

Air Conditioning Plant

Four York type $200\,\text{ton}$ R-236FA centrifugal compressor units, each having a chilled water pump rated at $900\,\text{GPM}$ at $70\,\text{PSI}$.

Potable Water Cure Time

A mandatory $30\,\text{minute}$ settling period after filling fresh water tanks before testing for total bromine resolution ($0.2\text{--}2\,\text{TBR}$).

Reverse Osmosis (RO) Desalination Plant

A desalination system using pressurized firemain ($700\text{--}1000\,\text{PSI}$) forced through semi-permeable membranes to produce potable water at $12,000\,\text{GPD}$ per unit.

Main Drainage System

An emergency dewatering system for AMR1, MER1, AMR2, MER2, and shaft alley driven by three eductors powered by firemain at minimum $120\,\text{PSI}$.

Vacuum Collecting, Holding, and Transfer System (VCHT)

A sewage collection system operating in AT SEA, IN PORT, or TRANSIT modes utilizing ejector pumps, discharge pumps, and holding tanks.

Fill and Drain Pump Unit (FADPU)

The fill, flushing, and transfer station for steering gear machinery that also serves as the emergency manual steering operating station.