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Back to: "I"induced flow
- Definição1
- The component of air flowing vertically through the rotor system resulting from the production of lift.
- Fonte1
- FEDERAL AVIATION ADMINISTRATION. Rotorcraft flying handbook (FAA-H-8083-21). Washington, DC: FAA, 2000. Disponível em: http://www.faa.gov/library/manuals/aircraft/media/faa-h-8083 -21.pdf. Acesso em: 10 fev. 2012.
- Definição2
- At flat pitch, air leaves the trailing edge of the rotor blade in the same direction it moved across the leading edge; no lift or induced flow is being produced.
- Fonte2
- FEDERAL AVIATION ADMINISTRATION. Helicopter flying handbook (FAA-H8083-21A). Washington, DC: FAA, 2012.
- Contexto
- As the rotor blades rotate they generate what is called rotational relative wind. This airflow is characterized as flowing parallel and opposite the rotor 's plane of rotation and striking perpendicular to the rotor blade's leading edge. This rotational relative wind is used to generate lift. As rotor blades produce lift, air is accelerated over the foil and projected downward. Anytime a helicopter is producing lift, it moves large masses of air vertically and down through the rotor system. This downwash or induced flow can significantly change the efficiency of the rotor system. Rotational relative wind combines with induced flow to form the resultant relative wind. As induced flow increases, resultant relative wind becomes less horizontal. Since angle of attack is determined by measuring the difference between the chord line and the resultant relative wind, as the resultant relative wind becomes less horizontal, angle of attack decreases.
- As the helicopter accelerates in forward flight, induced flow drops to near zero at the forward disc area and increases at the aft disc area. This increases the angle of attack at the front disc area causing the rotor blade to flap up, and reduces angle of attack at the aft disc area causing the rotor blade to flap down. Because the rotor acts like a gyro, maximum displacement occurs 90° in the direction of rotation. The result is a tendency for the helicopter to roll slightly to the right as it accelerates through approximately 20 knots or if the headwind is approximately 20 knots.
- Subárea1
- Rotorcraft
- Português
- fluxo induzido