Fundermentals Flashcards
Equation of Force
F=Mass x Acceleration
Equation of Weight
W=Mass x Gravity
What is work
Work is done when an object is moved over a distance
Equation of Work
W=Force/Distance
What is Power
The rate of doing work
Equation of Power
P=Work/Time
Unit of Force
Newton
Unit of Weight
Newton
Unit of Power
Watt
Unit of Work
Joule
Two Mechanical energy
Potential
Kinetic
What is potential energy
The energy a body has by virtue of its position
Equation of PE
PE=mgh
What is kinetic energy
The energy a body has by virtue of its motion
What is the equation of Kinetic energy
KE=1/2 x m x v^2
Newton’s First Law
Body will remain at rest or at a constant velocity unless an external force acts on it
Newton’s second law
The force on a mass causing it to accelerate is directly proportional to the force
F=ma
Newton’s third law
Every action has an equal and opposite reaction
The brayton cycle
The GTE is a heat engine using air as a working fluid to provide heat
Intermittent / continuous
Piston eng = intermittent
Turbine eng = continuous
Does pressure rise during combustion in a GTE eng
No, as it is not an I closed space
Does volume increase or decrease in a piston eng
Increase
Isobaric heating
There are no peak or fluctuating pressures
High/low octane fuel
Piston eng = high octane fuel
GTE eng = lower octane fuel
Turbo fan
Used on modern A/C high speeds, good efficiency
Turbo jet
Older type of GTE, very high speeds, very loud, large fuel intake
Turbo prop
Shaft power only, good speed for A/C size, good fuel efficiency
APU
Supplies electrical and pneumatic power
What is Jet propulsion
The propelling Force, which is generated in the opposite direction to the flow of mass
Called a reaction engine
How do we accelerate air
Increase pressure
Thrust of a turbo jet
Produces thrust by accelerating ambient air, produce high velocity gasses
Loud and not efficient
Thrust of a turbo prop
Produces thrust by accelerating a large amount of air with a propeller,
Prop is driven by the compressor or by a free turbine along a long centre drive shaft,
Reduction gear box is required,
Convert gas energy into torque,
Very efficient, not high speed
Thrust of a turbo fan
Usually twin or triple spool, Fan is driven by turbine, No reduction gearbox, Large amount of gas converted into torque to tribe fan and compressor, rest into thrust, Fan can produce 80% thrust
Bypass ration on a turbo fan
4:1 - 9:1
Prop fans
Number of fans and the shape allows the engines to have good speeds and alt capabilities
20% less fuel
Bypass ratio = 90:1
Non modular construction
Saves weight, complicated/difficult to access parts, older type
Modular construction
Modern design, pre assembled/balanced, easier to work on, easy to remove parts
Major modules of modular construction
Fan, core, accessory drive, LP turbine
Eng materials characteristics
Strong, lightweight and cheap
Al alloy
Gearbox housing, fan stator casings, fan module parts
Ceramic
Combustor and HP turbine
Steel alloys
N1 drive shaft, eng bearings, main structural frames
Cobalt alloys
Stator of first stage of the HP turbine
Titanium alloys
Fan, LP compressor, front stage of HP compressor
Nickel alloys
HP compressor, combustion section, HP/LP turbines
