Question

why fan has three wings

Answer 1

the main purpose of an electric fan is to create air-flow. So, a good fan must create a good air-flow with minimal noise. Usually an electric fan has a shaft which is rotated at a moderate speed by an electric motor. The speed of electric fans is chosen in a moderate level for safety purpose and to reduce the noise produced when a fan is operated. There are blades attached to this shaft which rotate along with the shaft.


The number of blades and their shape may vary depending upon the model and aesthetic sense. Even there are certain fans with only one blade. These are usually meant for aeroplane propellers.

Fans may have any number of blades placed at any position. But the weight of the blades must be balanced so that there is maximum efficiency. For that reason, fans with only one blade is not often preferred, as the weight of the blade tend to bend the blade down.

Coming to the arrangement of fans with two blades, it is obvious that these two blades must be oppositely arranged to each other. Similarly in the case of having three blades, each of them must make an angle of 120 degrees with the next blade. 

Answer 2

fans have not only three wings. it has 2 or 4 also. it depends how much air you need!!
am I right!!