Linear wind

The Linear wind enables you to define a linear variation of the wind speed and/or wind direction. The defining parameters are listed below and illustrated in the following figure:




The equation defining the linear wind can be found in the Linear wind document of the Theory manual.

 

Linear

Start speed

The start (initial) speed.

For more information on how the linear wind is computed, check the Linear wind section in the theory manual

  • Default value: 3
  • Unit: ${\text{m}} \over {\text{s}}$
  • Range: -100 — 100

End speed

The end speed.


  • Default value: 25
  • Unit: ${\text{m}} \over {\text{s}}$
  • Range: -100 — 100

Start angle

The start angle.


  • Default value: 0
  • Unit: $°$
  • Range: -360 — 360

End angle

The ending angle.


  • Default value: 0
  • Unit: $°$
  • Range: -360 — 360

Start-up duration

Duration until first speed/angle change


  • Default value: 10
  • Unit: $\text{s}$
  • Range: 0 — 1e+06

Duration

Duration of the linear increase.


  • Default value: 20
  • Unit: $\text{s}$
  • Range: 0.1 — 1e+06

Shear profile

Shear

Decides if a shear law is applied to the deterministic wind.


  • Default value: False
  • Unit:

Power law exponent

The shear is computed using a power law. This is the power law exponent.

To see how the power law is computed, see Wind profile power law

  • Default value: 0.2
  • Unit:
  • Range: 0 — 100

Reference height scheme

This parameter lets your define whether the point of application of the reference speed (used to compute a vertical wind shear) is input by you or defined as the hub height. This parameter is only relevant if a shear law is applied to the wind. 

IHub height is selected, the reference wind speed for the shear will be applied at hub height. If the turbine has multiple rotors, the reference wind speed will be applied at the average hub height. If there is no rotor, the reference speed is applied at the average height of the nodes at sea level. 

Options:

Hub height (default):

The reference height is set to the hub height.

User defined:

The reference height is set explicitly by the user (you).

Reference height

The height above the ground (or above sea level for offshore turbine) where the reference wind speed is applied.

Hub height is often used for the reference height, but in some cases it is convenient to use another height. E.g. if the wind speed is given for a height of 10 m above ground, then this parameter should be set to 10 m. Note: The reference height only has an influence if there is shear (see Wind profile power law)

  • Default value: 10
  • Unit: $\text{m}$
  • Range: 0.01 — 1000