Question

Which type of vertical wind machine has relatively low solidity and low starting torques?

(a) Cup anemometer

(b) Savonius rotor

(c) Darrieus type rotor

(d) Magnus effect rotor

This question was posed to me in unit test.

My doubt is from Vertical Axis Wind Mill topic in chapter Wind Energy of Energy Engineering

Answer 1

Right option is (c) Darrieus type rotor

Explanation: Darrieus type rotors are lift devices characterized by curved blades with air foil cross sections. They have relatively low solidity and low starting torques, but high tip to wind speeds and therefore relatively high power outputs per given rotor weight and cost.