Turbine data: Tower

Data to define the tower and parameterise the models used in the tower disturbance calculation.

Tower influence

Used to account for the effect of the tower on the turbine inflow.

• None. No tower influence model is active.
• Potential. The classical potential theory model is applied.
• Bak. Bak's model, incorporating a correction to the potential, is applied. This model is parameterised by the tower drag coefficient.

Tower shadow

Used when modelling downwind rotors, to introduce an additional tower wake velocity deficit into the tower disturbance calculation.

• None. No tower shadow model is active.
• Powles. A $\cos^2$ shaped velocity deficit model is applied. This model is parameterised by the tower drag coefficient.
• Eames. A Gaussian shaped velocity deficit model is applied. This model is parameterised by both the tower drag coefficient and the tower turbulence intensity.

If tower influence and tower shadow are both none, the remaining data on the tower page do not apply, and the undisturbed wind field is used to calculate the turbine's aerodynamic loading. Otherwise, the following data are presented:

Tower connection

Each end of the tower can be fixed, anchored or connected to another object. The tower cannot be connected to the turbine.

Position

Defines the position of the tower ends in terms of the connection coordinates $x$, $y$ and $z$.

Tower profile data

These profiles are defined at a number of discrete unstretched arc lengths along the tower length, starting at end A. The data are assumed to vary linearly between the arc lengths at which they are given.

Outer diameter

The outer diameter of the tower.

Drag coefficient

The drag coefficient of the tower. Only available if the Bak tower influence model, or either tower shadow model, is selected.

Turbulence intensity

The average turbulence inflow intensity. Only available if the Eames tower shadow model is selected, in which case, a value greater that 0.05 must be specified for the turbulence intensity.