491 likes | 878 Views
Gas Turbine Applications. LM 2500, Allison 501, The Plant. Objectives. LM 2500 Gas Turbine Engine - specific components, specifications, systems Allison 501 Gas Turbine Generator Set - purpose and operation Interrelationship of supporting systems and operations Engineering plant lineups.
E N D
Gas Turbine Applications LM 2500, Allison 501, The Plant
Objectives • LM 2500 Gas Turbine Engine - specific components, specifications, systems • Allison 501 Gas Turbine Generator Set - purpose and operation • Interrelationship of supporting systems and operations • Engineering plant lineups
Engineering Plant Layout Spruance Class Destroyers
GAS TURBINE ENGINESLM 2500GAS TURBINE GENERATORSALLISON 501-k 17
LM 2500 • In DDG’s and CG’s, have 4 engines • In FFG’s, have 2 engines • Engines are shock mounted to minimize noise and allow for protection • Advantages of LM 2500 • Compact & light • Easy to maintain & repair • Quick start time (~ 1 min)
LM 2500 Components • Starter • Pneumatic - driven by pressurized air • Compressor • 16-stage, axial flow (17:1 compression ratio) • Has some controllable pitch vanes to provide proper air flow and prevent stall
LM 2500 Components • Combustion Chamber • Annular design • 30 fuel nozzles
LM 2500 Components • Gas Generator Turbine • HP Element only • High speed • Power Turbine • Split shaft to allow varying output speeds while maintaining constant generation of energy • 6 sets of nozzles and blades • Lower speed than GGT
LM 2500 Engine Control • Gas Generator Turbine • Produces energy available for power turbine • Controlled by throttles - alters fuel flow • Runs at set continuous RPM • Power Turbine • Speed depends on quantity of exhaust gases from gas generator turbine & propulsion load • Double helical, double reduction, locked train reduction gears
LM 2500 Characteristics • Stage efficiency = 92.5% • R&D: 30,000+ hrs of op-testing • Two versions available: • LM 2500-20 (22,500 shp) • LM 2500-30 (30,000 shp) – USN warships
LM 2500 Engine Control • Speed Governor • Used to prevent power turbine from exceeding speed limit (104%) • Reduces fuel to gas generator section which reduces gases to power turbine • Overspeed Trip • If governor fails, trip secures fuel to LM 2500 to shut it down (108%)
Air Intake & Exhaust • Must minimize space and weight • Must keep air inlet losses to a minimum to ensure maximum performance • Intake has screens/filters to ensure clean, filtered air at all times
INTAKE DUCTS • Located to prevent ingestion of SW • NBC considerations • Contains • Demisters • Intake Heaters • Blow-in Doors • Allows engine removal • FOD screen • Silencers • Separator Pads
Air Intake & Exhaust • Exhaust generates thermal and acoustic problems • Possible damage to personnel & equipment • Increased detection & weapons guidance from heat (IR signature) • Silencers and eductor nozzles used to silence and cool exhaust
EXHAUST DUCTS • Routes exhaust gases to atmosphere • Contains • Silencers • Exhaust Gas Cooling • Higher than intake
Allison 501 Gas Turbine Generator Set (GTGS) • Used to generate electricity • Three 2000KW GTGS • Any two can supply electrical needs of ship • Separated by 3 water-tight bulkheads to minimize potential battle damage • Single Shaft • Waste Heat Boiler • Uses heat of exhaust to generate low pressure steam for auxiliary purposes
SAFETY FEATURES • AUTOMATIC SHUTDOWNS : • HIGH VIBRATION (GAS GENERATOR AND/OR POWER TURBINE) • COOLING SYSTEM FAILURE • MODULE FIRE (TEMP AND UV SENSORS) • HIGH TURBINE INLET TEMPERATURE (1530 F) • LOW LUBE OIL PRESSURE (6 PSIG) • POWER TURBINE OVERSPEED • BATTLE OVERRIDE • INHIBITS ALL AUTOMATIC SHUTDOWNS EXCEPT TURBINE OVERSPEED, USED ONLY WITH COMMANDING OFFICER PERMISSION
CRP Propeller & Propulsion Shafting • Shaft is hollow to provide flow of oil to propellers • LM 2500 cannot operate at < 5,000 RPM (corresponds to ~11 kts for DDG) • Pitch of blades controlled hydraulically through pistons and gears • Pitch must be adjusted to go slower than 11 kts
CRP Propeller & Propulsion Shafting • In order to go faster than 11 kts, shaft RPM increased • In order to go astern, pitch varied to reverse flow • Overall purpose • Controllable pitch to improve efficiency • Reversible to allow for ahead/astern flow with single direction rotation of shaft
PURPOSE OF AUXILIARY EQUIPMENT Equipment which is used to support the operation of the engineering plants as well as other equipment throughout the ship
SPECIFIC AUXILIARY EQUIPMENT (Spruance) • AC Units • 3-4 units • Used for AC or refrigeration • Sewage Plants • typically 2 • Fire Pumps • 6 pumps • Multiple will always be available
SPECIFIC AUXILIARY EQUIPMENT (Spruance) • Waste Heat Boilers • 3 boilers (one next to each GTGS) • Used for hot water heaters, distilling plant, galley, heating, etc. • Evaporators (2 in same location) • Seawater Pumps (3) • HP/LP Air Compressors • 2 HP, 2 LP
DD-963 CLASS CONTROLS • Engineering Control and Surveillance System (ECSS) • Automated electronic control and monitoring system for main propulsion turbines, generating sets, and most auxiliaries • Monitor and provide printout of major engineering parameters
DD-963 CLASS CONTROLS • Signal from bridge routed through the Propulsion and Auxiliary Control Console (PACC) in the central control station and then through the Propulsion Local Control Console (PLCC) in each main engineering room
Plant Lineups • LM 2500’s connected to reduction gears via pneumatic clutch • Three possible lineups • Full Power • Split Plant • Trail Shaft
Plant Lineups • Full Power Lineup • 2 turbines/shaft with 2 shafts (4 turbines) • Max speed > 30+ kts • Split Plant Lineup • 1 turbine/shaft with 2 shafts (2 turbines) • Max speed = 30 kts • Trail Shaft Lineup • 1 turbine/shaft with 1 shaft (1 turbine) • Other shaft windmilling • Max speed = 19 kts
ADVANTAGES OF THE PROPULSION PLANT L/U’S • Readiness: quick S/U times • Fuel Costs: most cruising speeds can be done on one engine • Maintenance: less overall run time on each engine • Reliability: have 4 engines • Personnel Requirements: fewer watchstanders needed
Operation of the Allison T-56 turboprop engine • Single shaft construction • Construction characteristics • 14 stage compressor • can-annular combustor • 4 stage turbine rotor - drives the compressor, accessory gear drive, propeller reduction gear assembly, and the hot exhaust gases are directed through a nozzle producing additional thrust
Operation of aircraft engines and their naval applications • Turbojet engine • used aboard A-6 and A-4 aircraft • develops thrust due to expansion of escaping exhaust gases • turbine drives the compressor and auxiliaries
Operation of aircraft engines and their naval applications • Turbofan engine • used aboard F/A-18, A-7, AV-8 aircraft • turbine drives a fan which compresses large volumes of air, the expansion of this air from the fan provides the thrust for the aircraft • advantages over turbojet include: lower fuel consumption, lower noise level, produces more thrust for shorter takeoffs
Use of gas turbine propulsion engines in motor vehicle applications • Humvee • A-1 Abrams Tank