Rotating Frame
Centrifugal, Coriolis, and Euler forces are “fictitious” volume forces that need to be introduced in a rotating frame of reference, since it is not in an inertial system. The Rotating Frame node adds the effect of these forces.
The Rotating Frame node defines a local coordinate system in which the selected object is rotating around the local z-axis.
One Rotating Frame node must be added for each rotor included in the model to define it’s axis of rotation, and angular velocity.
Axis of Rotation
Define the Axis of rotating, Local x direction, and Axis of rotation base point.
Axis of Rotation
Select an Axis of rotating — x-axis, y-axis, z-axis, From point selection, From edge selection, or User defined.
If User defined is selected, specify the direction of the axis of rotation.
If From point selection is selected, two point selections are shown. Select one or multiple points in the Axis of rotation Point Selection 1 and Axis of rotation Point Selection 2.
If From edge selection is selected, one edge selection appears. Select one or multiple edges in the Axis of rotation Edge Selection.
Local x Direction
Select a Local x direction — Automatic, x-axis, y-axis, z-axis, x-axis (negative direction), y-axis (negative direction), z-axis (negative direction), or User defined. If User defined is selected, specify the direction of the local x direction.
Note that axes parallel to the Axis of rotating are not available on the Local x direction list, and only the Automatic and User defined options are available if Axis of rotating is selected as From point selection, From edge selection, or User defined.
Table 4-1: Automatic Local x direction.
Axis of rotation (Local z direction)
Local x direction
Local y direction
x-axis
y-axis
z-axis
y-axis
x-axis (negative direction)
z-axis
z-axis
x-axis
y-axis
Axis of Rotation Base Point
If Axis of rotating is selected as x-axis, y-axis, z-axis, or User defined, specify a spatial coordinates of the base point for the axis of rotation.
Rotational Velocity
Select from the list how the rotational velocity is specified:
•
Choose Constant angular velocity or General angular velocity to specify the rotational velocity ωr in the unit rad/s.
•
Choose Constant revolutions per time or General revolutions per time to specify the rotational velocity Ωr in the unit 1/s.
For time-dependent study types, specify the Initial angle φ0.
The Constant and General rotational velocity options are identical for stationary and frequency study types. If either of the General options are selected, the rotational velocity can depend on time.
Spin Softening
The Spin Softening checkbox (only present in the Solid Rotor interface) is selected by default. When spin softening is included an extra contribution to the centrifugal and Euler forces from deformation is taking into account.
Location in User Interface
Context Menus
Solid Rotor > Rotating Frame
Solid Rotor, Fixed Frame > Rotating Frame
Ribbon
Physics tab with Solid Rotor selected:
Domains > Solid Rotor > Rotating Frame
Physics tab with Solid Rotor, Fixed Frame selected:
Domains > Solid Rotor, Fixed Frame > Rotating Frame