Turbine data
$\newcommand{\Txyz}{\mat{T}\urm{xyz}}$

Name

Used to refer to the turbine.

Connection

A turbine can be fixed, anchored or connected to another object.

Initial position

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

Initial orientation

The azimuth, declination and gamma angles, $\phi, \theta, \gamma$, that define the orientation, $\Txyz$, of the turbine frame relative to the connection axes, $\Cxyz$. The turbine main rotor shaft rotates about the turbine's $z$-axis. These angles specify the orientation of the turbine frame as follows:

  1. rotate $\Txyz$ by an angle $\phi$ about $T\urm{z}$ ($= C\urm{z}$ at this point)
  2. rotate by an angle $\theta$ about the resulting $T\urm{y}$ direction
  3. rotate by an angle $\gamma$ about the resulting (and final) $T\urm{z}$ direction

As usual, positive rotations are clockwise when looking in the direction of the axis of rotation.

Three-dimensional rotations are notoriously difficult to describe and visualise. When setting the orientation, it is best to check that the resulting $\Txyz$ directions are correct by drawing the local axes on the 3D view.

Rotation sense

The direction the rotor is designed to spin, when viewed from upwind. It dictates: how the blade profile is interpreted; how the inflow angles are defined, the directions in which the aerodynamic lift and pitching moment act; the conventions used for generator/pitch control; and some turbine results. For a conventional wind turbine, the rotation sense is clockwise. Some downwind turbines use an anticlockwise rotation sense.

Notes: Blades are numbered moving around the rotor in the direction of the rotation sense, when viewed from upwind. This is used to identify the blades when asking for certain turbine results, connecting objects to turbine blades, or using individual pitch control.

Imposed motion consistent with solver

Determines whether OrcaFlex should modify the imposed velocity and acceleration values to be consistent with the implicit integration scheme. This data is only relevant when the turbine uses the specified rotation generator mode or makes use of a pitch controller.

Characteristic scales

For some models it may be desirable to explicitly set a characteristic length and characteristic force for the turbine. These characteristic scales directly affect the convergence criteria of the iterative solvers employed in the analysis. The data does not appear on the turbine data form but can be found on the all objects data form.