IG Flashcards
Theory of reciprocating engine
Suck squeeze bang blow
Closed and intermittent
Otto cycle
Theory of GTE engine
Open and continous
Braytton cycle
Intake compression combustion exhaust
2 types of energy
Potential
Kinetic
Define potential energy
Enegery stored in an object due to thier form or position
Define kinetic energy
Energy in a object with motion
Outline conservation of energy
Energy can neither be created nor destroyed, it can only change forms
Measurement of power
Joules
P=W/t
Outline how heat effects matter
When matter is heated, the particles have more energy and move further apart
3 gas laws
Charles law
Boyles law
General gas law
Outline Charles law
Pressure constant.
When gas heated (temperature increase), volume increases
Outline Boyles law
Temp remains constant
Pressure decreases and volume of container increases
3 ways of heat transfer
Conduction -physical touch
Convection - fluid
Radiation - waves
Types of GTE
Turbine fan
Turboshaft
Turboprop
Turbojet
Factors effecting thrust
Temperature Altitude Airspeed Engine speed Fan efficiency
Outline how temp effects thrust
Lower temp is more dense so more thrust can be produced
Altitude effects thrust
When altitude increases thrust decreases (less dense)
Airspeed effect thrust
Forward airspeed increases air mass acceleration in engine decreases which results in less thrust produced.
However
When forward airspeed increases more air is forced into engine. Known as ram effect and results in more pressure therefore more thrust produced
Engine speed effect thrust
At high engine speed a small increase in rpm will equal large increase kn thrust.
While low engine speed with a large increase of speed equals small increase in thrust
Fan efficiency effect thrust
Turbo fans can produce same thrust as turbojet but with less fuel required
Function of inlet
Recover as much of the total pressure of the free airstream as possible and deliver it to the compressor
Types of inlet [6]
Bellmouth Subsonic Supersonic Fuselage mounted Wing mounted Engine mounted inlets
Compressor damage
Erosion
FOD
Purpose of compressor
To increase pressure of airnin engine. More air forced in the more thrust can be produced
2 ways to prevent fod in compressor
Inlet screen,
Vortex dissipater
Inlet warning
Magnesium thorium, use appropriate ppe when filings or dust are present. They are radio active and must not be injested
Compressor purpose
A device that raises the pressure of a working fluid passing through it
Compressore shape
Convergent. To raise velocity
Cuase of compressor stall
AOA to great
Highest pressure in an engine
Diffuser
Exit guide vanes from a compressor
Straighten and smooth the airflow into the diffuser and prepare it for combustion
5 bleed air from diffuser
Turbine cooling Bearing seal pressurisation Engine anti icing Customer services Pneumatic starting
Outline Air for combustion
Primary air 25-35% used for combustion
Secondary air used for shaping and cooling
Best fuel to air ratio
15:1
Turbine components
Case
Stator
Shroud
Rotor
Purpose of turbine
To extract sufficient kinetic energy from expanding gasses to drive the compressor and engine accessory gearbox
Purpose shrouded turbine blades
Reduces vibration
Increases efficiency
Where open ended turbine blades found
Higher rotational speed turbines
Where shrouded turbine blades found
Used on slower rotational speed turbines
2 types of turbine cooling
Convection/film
Transpiration - stationary blades only
3 parts of exhaust section
Exhaust nozzle
Tailpipe
Exhaust cone
Purpose of exhaust cone
Channel, collect and discharge gasses in a single jet
Purpose of tail pipe
Directs exhaust gasses safely to exhaust nozzle
Purpose of exhaust nozzle
Provide an extra boost in gas velocity, by its convergent shape
What is compressor stall and when it occur
Inbalance between inlet velocity airflow and compressor rotational speed.
Occurs when AoA on compressor blade is too great
Safety precautions for working on fire systems
- Detectors must be clear of other components
- Fire wire must not be crushed or damaged
- Clip grommetsust not be crushed
- Fire wire bend tolerances to be observed
Purposes of compressor exit guide vanes
Last stage in compressor, and they remove the swirl from airflow prior to entering diffuser
Why turbo prop more efficient at lower speed
Over 375mph aerodynamic drag and tip shock stall to great
