An aircraft propeller is an aerodynamic device which converts rotational energy into propulsive force creating thrust which is approximately perpendicular to its plane of rotation. The rotational energy can be produced by a piston or gas turbine engine or, in limited applications, by an electric motor. A turboprop engine is a turbojet engine in which a portion of the exhaust energy is used to drive a propeller
The total energy () at the nozzle exit can be expressed as:
where,
- E is the Total Energy, i.e sum of kinetic and potential energy
- is the static enthalpy at the nozzle exit,
- is the velocity of the exhaust gases relative to the reference frame of the exhaust gases