Why fan blades are twisted?

Question

Usually fans ceiling fan, or cooling tower fans or exhaust fans are twisted why it is so? Plz tell the technical reasons behind that

Answer 1

A fan or propeller is shaped so that the tip spins faster than the centre (fans have more than two blades). The blades are twisted, steep in the middle, less so at the edge, which allows the thrust to keep it moving. Your blow gives it the initial force. As the fan rotates the blades push the air in one direction and experience a reaction force in the opposite direction as a result. Each experiences a "lift" force, typically called "thrust," in the direction opposite the airflow.

The physics is similar to that of an aerofoil (the shape of a wing). A fan is just like a spinning wing.

“As a wing moves through air, the air is split and passes above and below the wing. The wing’s upper surface is shaped so the air rushing over the top speeds up and stretches out. This decreases the air pressure above the wing. The air flowing below the wing moves in a straighter line, so its speed and air pressure remain the same.
Since high air pressure always moves toward low air pressure, the air below the wing pushes upward toward the air above the wing. The wing is in the middle, and the whole wing is “lifted.” The faster an airplane moves, the more lift there is. And when the force of lift is greater than the force of gravity, the airplane is able to fly.”

Answer 2

Exhaust Fan Blades

Answer 3

Air fans are twisted along their blade lengths because the speed of the fan blade's cross section increases with the radius. If you were to design the optimum aerofoil cross section for a given fixed speed, you will notice that at low speeds, the cross section would have a significant attack angle and a more pronounced bulge, while at higher speeds the attack angle would be less, and the blade flatter. If you put the different cross sections for different speeds along the fan blade, you will end up with a twisted blade. Design of water propellers are twisted for the same reason, although the physics of ideal cross sections are different.

Answer 4

Ceiling fans are normally used as a cooling device in warm months by pushing air down from above, thereby creating a wind chill effect. In winter months, a ceiling fan can act as a heat transferrer by reversing the direction of the blades. By doing so, the fan pulls air up, thereby pushing the warmer air that stratifies near the ceiling down along the walls; as long as the fan is set at a low speed, this will not create a wind chill. A fan on reverse has the leading edge of the fan blades being the downward edge; in most cases this rotation is clockwise when the operator is standing below and looking upwards at the fan.

Answer 5

If they weren't twisted, they wouldn't be pushing air, but slicing through the air and not exactly moving anything. The ones with bigger blades that look more like flower petals have a larger surface area, thus being able to push more air than a plain old ceiling fan with blades of the same size.

Answer 6

In order to push air in required direction the blades of fan are twisted

Answer 7

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RE:
Why fan blades are twisted?
Usually fans ceiling fan, or cooling tower fans or exhaust fans are twisted why it is so? Plz tell the technical reasons behind that

Answer 8

Fan blades push or pull air. Look up the Wright Brothers and see they invented a wind-tunnel to perfect propellers. They still use the design today.

Answer 9

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Answer 10

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