What are the 2 purposes of an airplane propulsion system?
- Thrust balances drag (Flight at same speed)
- Thrust exceeds drag (Acceleration)
What is a propulsion system?
Machine that produces thrust to push an object forward
What is excess thrust?
Difference between thrust and drag
What are the 4 major forces acting on an aircraft?
- Lift L (orthogonal to flight path)
- Drag D (parallel and opposite to flight direction)
- Weight W (pointed towards earth at angle q relative to L)
- Thrust T (at an angle relative to the flight path)
What force has to be generated by the thrust for constant flight?
It has to be opposite in direction but equal in magnitude to the sum of D, W and L
What is the energy conversion chain for thrust generation?
- Energy source (e.g. cerosine) (bound energy)
- Power generation (e.g. gas turbine) (net power)
- Propulsion generation (e.g. Propeller) (propulsive power)
- Thrust
What are the 2 main principal propulsion systems?
- Propeller (mechanical acceleration)
- Jet propulsion (thermal acceleration)
How is thrust produced in a jet propulsion system and what are the 3 energy sources?
- Thrust produced solely or in part by a high-speed gas exhaust (jet) from inside the engine
- Chemical, thermic or nuclear energy
What are 5 examples of jet propulsion systems?
- Gas turbine (turbo-jet) engine
- Ram jet
- Pulse jet
- Rocket engine
- Turbo rocket
What thermodynamic cycle is used in gas turbines?
Joule Brayton cycle
What are the 5 stages in a turbo-jet engine and what is their purpose?
- Inlet: Intake of mass flow, compression by deceleration of fluid
- Compressor: Work input to compress a fluid to a high pressure
- Combustion chamber: Fuel mass flow input and ignition, heat addition leads to high temperatures
- Turbine: Work output and expansion of the fluid, work needed for the compressor
- Nozzle: Acceleration of fluid to a high velocity by the expansion of the fluid
What are the 4 basic requirements for aero engines?
- Guarantee Thrust/Power in Design and Operation
- Safety
- Reliability
- Certification Requirements
What are 9 types of turbo-jet engines?
- Twin-spool by-pass turbo-jet
- Triple-spool front fan turbo-jet
- Prop-fan
- Contra-rotating fan-concept
- Double-entry single stage centrifugal turbo-jet
- Single-entry two-stage centrifugal turbo-propeller
- Twin-spool axial flow turbo-propeller
- Single-spool axial flow turbo-jet
- Twin-spool turbo-shaft
How can turbomachines be classified?
By flow direction:
- Axialcompressor
- Diagonalcompressor
- Radialcompressor
