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The mechanism of a fan

  1. Sep 18, 2006 #1
    can anybody help me to find the answer of this question?

    a fan ( or a propellor) rotates sidewise, but the air goes making a perpendicular with the axis of its motion.. I know that there is vector involved in this, but how does it work?
  2. jcsd
  3. Sep 18, 2006 #2
    Normal forces are perpendicular to the surface, so whenever a fan wing hits a molecule, it accelerates it in the direction perpendicular to the plane of the wing.
  4. Sep 19, 2006 #3


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    So there is a slight hellical rotation in the fan airstream which is generally ignored.

  5. Sep 21, 2006 #4
    The twist in the fan's "arm" make the air change direction when moving. This change of direction creates a reaction on the fan itself. This reaction acts as a force on the whole device.

    If you want, the process is the same as for planes flying. The air passing under the wing of the plane is deviated downward, creating a force upward on the wing.
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