Question

With upto how many propellers can windmills are built?

(a) 4

(b) 2

(c) 7

(d) 6

The question was posed to me in a job interview.

Question is taken from Horizontal Axis Wind Mill in chapter Wind Energy of Energy Engineering

Answer 1

Right choice is (d) 6

Best explanation: Wind turbines have been built with upto six propellers type blades but two and three bladed propellers are most common. A one bladed rotor with a balancing counter weight has some advantages, including lower weight and cost and simpler controls, over the multi-bladed type.