15.1 Flashcards
Potential energy
Energy due to virtue of position
Kinetic energy
Energy due to virtue of motion
Newton 1st law
Law of inertia
Newton’s second law
Force = mass x acceleration
Newton third law
Every action has an opposite and equal reaction
How many changes of state
4
Isobaric
Isochoric
Isothermal
Isentropic
What is the Brayton cycle
Thermodynamic cycle of a gas turbine engine that produces thrust
What’s the difference between piston engine working cycle and GTE working cycle
Piston is intermittent whereas GTE is continuous
What is isobaric heating
Heating at a constant pressure
Piston engine peak pressure
Excess of 1000psi
During combustion does pressure of the air increase
Pressure of air doesn’t increase
What happens to air during suck
An increase of pressure and decrease in volume
What happens to air in the compressor
Compressed which gives large increase in pressure and decrease in volume
What happens to air during expansion
Pressure is constant but increase in volume
Velocity energy is converted into mechanical energy by a turbine
What happens to air in the exhaust section
Converts expanding volume and decreasing pressure of gases to a final high velocity
2 important changes of state in GTE
Isobaric and isentropic
What’s the main function of an aircraft engine
Create necessary movement of the aircraft (thrust)
Advantage of piston engine
More fuel efficient
Disadvantage to piston engine
Performance decreases as altitude does
Too large for aircraft
What’s another name for a turbo shaft engine
APU
What is the bypass ratio
Air coming into engine vs coming out
Advantage of turbojet
Very high speed
Disadvantage of turbojet
Very loud
How does turbofan work better then turbojet
Fans at front of engine produce 80% off thrust
Quieter and better fuel consumption
What is a spool
Turbine driving a compressor through a shaft
What does an twin spool arrangement have
HP compressor and turbine & LP compressor and turbine
What does triple spool arrangement have
HP , IP , LP Compressors and turbines
Difference between turboprop and turbojet
Turboprop has additional turbines , power shaft , and reduction gearbox
Turboprop most efficient mid-range speed and altitude
Speed - 250-400 knots
Altitude - 18000-30000 ft
What parts are in the cold section
Parts of the engine from inlets to compressors/diffuser
What parts are in the hot section
Areas past compressors from the combustion chamber to the exhaust
What construction does a GTE consist of
Modular construction
Advantages to modular construction
Modules easily removed and replaced and no rebalancing
What area is 0-2 isentropic
Compression stage pressure increases volume decreeses
3-5 isentropic
Expansion process
What process is 2-3
Isobaric heating in combustion chamber
What is 3-4 stage
Expanded gases into mechanical power by turbine and jet pipe
What kind of materials do we need for the engine
Light and cheap as possible
