How are the following variables defined in Bladed?
- Support structure deflections / velocities / accelerations
- Support structure globlal positions / velocities / accelerations
Support structure deflections:
• Tower proximal node coordinates i.e. tower base or modal reference node coordinates. For a fixed base turbine, this aligns with global coordinates
o Translational deflection relative to tower base.
o Rotational deflection relative to tower base output as rotation vector (axis-angle convention*)
Support structure velocities:
• Tower proximal node (tower base) coordinates.
o Translational velocity relative to tower base.
o Rotational velocity relative to tower base output as rotation vector (axis-angle convention*)
Support structure accelerations:
• Tower proximal node (tower base) coordinates.
o Translational acceleration relative to tower base.
o Rotational acceleration relative to tower base output as rotation vector (axis-angle convention*)
Support structure global positions:
• Global position of support structure node, in global coordinates.
o Position relative to global (0,0,0)
o Orientation relative to global coordinate system. For a fixed base turbines, all support structure nodes initially have the same orientation as the global coordinate system.
Support structure global velocities:
• Global velocity of support structure node, in global coordinates.
o Absolute translational velocity of node
o Absolute angular velocity of node
Support structure global accelerations:
• Global acceleration of support structure node, in global coordinates.
o Absolute translational acceleration of node
o Absolute angular acceleration of node
* The axis-angle convention refers to the convention used to output rotation angles. This means that the rotational displacement from the undeflected orientation is considered as a single rotation about an axis. This rotation can be expressed as 3 orthogonal vectors aligned with e.g. the tower base coordinates. The 3 components of this rotation vector are output as the x, y and z rotational displacements.