2. GT LECTURE OUTLINE
Introduction
GT off-design performance and control
Monitoring, diagnosis and plant flexibility
Blade Cooling Technologies
Gas Turbine Fuel Flexibility and Contaminants
3.
4.
5. FUEL CONSUMPTION TREND
1950 1960 1970 1980 1990 2000 2010 2020
JT8D
JT9D
PW4052
PW4084
Fuel
Burn
Year
Future
Turbofan
• U.S. airlines, hammered by soaring oil prices, will spend $5
billion more on fuel this year or even a greater sum, draining
already thin cash reserves
• Airlines are among the industries hardest hit by high oil prices,
which have jumped 38 percent in just 12 months.
• Airline stocks fell at the open of trading as a spike in crude-oil
futures weighed on the sector
10. MAJOR GAS TURBINE ENGINE COMPONENTS
1. Inlet:
– Continuously draw air into engine through inlet
– Slows, or diffuses, to compressor
2. Compressor / Fan:
– Compresses air
– Generally two, or three, compressors in series
– Raises stagnation temperature and pressure (enthalpy) of flow
– Work is done on the air
3. Combustor:
– Combustion or burning processes
– Adds fuel to compressed air and burns it
– Converts chemical to thermal energy
– Process takes place at relatively constant pressure
12. MAJOR GAS TURBINE ENGINE COMPONENTS
4. Turbine:
– Generally two or three turbines in series
– Turbine powers, or drives, the compressor
– Exhaust gas is expanded through turbine (P & T ↓)
– Work is done by the gas on the blades
– Use some of that work to drive compressor
– Next:
• Expand in a nozzle
– Convert thermal to kinetic energy (turbojet)
– Burning may occur in duct downstream of turbine (afterburner)
• Expand through another turbine
– Use this extracted work to drive a fan (turbofan)
5. Nozzle or Generator:
– Flow is ejected back into the atmosphere, but with increased
momentum (Nozzle)
– Raises velocity of exiting mass flow (Nozzle)
Or
- To convert mechanical energy into electrical energy (Generator)
13. AIRCRAFT ENGINE MANUFACTURERS
3 Major Aircraft Manufacturers in World Today (Commercial and Military)
1. Pratt and Whitney (USA)
2. General Electric (USA)
3. Rolls Royce (GB)
• Applications for Gas Turbines
– Commercial and Military Aircraft Engines, Helicopters
– Industrial (marine turbines, yachts, assault ships, etc.)
– Power Plants
• Interesting Note:
– Companies sell product at a $$ loss
– Profit is made many years later on refurbishment, spare parts, maintenance
15. 2. COMPRESSORS: WHERE IN ENGINE? PW2000
Fan
Compressor
Purpose of fan is to increase efficiency of turbojet engine
Much of air bypasses core of engine
16. TURBOFAN ENGINES
Bypass Air
Core Air
Bypass Ratio, B, a:
Ratio of by pass air flow rate to core flow rate
Example: Bypass ratio of 6:1 means that air volume flowing through fan and
bypassing core engine is six times air volume flowing through core
24. • Why film cooling?
– Turbine inlet temperatures > melting temperatures of turbine blade
materials
• Air provides a thin, cool, insulating blanket along external surface of turbine
blade
Example of Film-Cooled 1st Turbine Blade
Cooling
Holes
Editor's Notes
Le Turbine che lavorano a 60 Hz hanno limitazioni sull’altezza delle pale del compressore perchè eccessivamente sollecitati a trazione e quindi hanno sezioni di passaggio più piccole, elaborano portate più piccole e fanno meno potenza
