Wind Engineering - Wind Turbines

Wind Turbines

Wind turbines are affected by wind shear. Vertical wind-speed profiles result in different wind speeds at the blades nearest to the ground level compared to those at the top of blade travel, and this in turn affects the turbine operation. The wind gradient can create a large bending moment in the shaft of a two bladed turbine when the blades are vertical. The reduced wind gradient over water means shorter and less expensive wind turbine towers can be used in shallow seas.

For wind turbine engineering, wind speed variation with height is often approximated using a power law:

where:

= velocity of the wind at height

= velocity of the wind at some reference height

= Hellman exponent (aka power law exponent or shear exponent) (~= 1/7 in neutral flow, but can be >1)