Defining the Rotor Blade Motion

To account for the motion of the rotor blades, you define two motions—a rotation motion and a morphing motion. The rotation motion accounts for the rigid rotation of the external beam regions. The morphing motion updates the fluid mesh based on the imported displacement data.

The rotation motion requires two coordinate systems: a coordinate system that rotates with the rotor (a managed coordinate system), and a stationary coordinate system. The rotating coordinate system is identical to the stationary coordinate system at the initial conditions, that is, at t = 0.
To create the rotating coordinate system:
  1. Right-click the Tools > Coordinate Systems > Laboratory > Local Coordinate Systems node and select New > Cartesian.
  2. In the Create Cartesian Coordinate System dialog, accept the default axis definition by clicking Create and Close.
    At the initial conditions the azimuth angle is zero. Therefore, the angle between the laboratory coordinate system and the rotating coordinate system is also zero and you can use the default axis definition.
  3. Rename Local Coordinate Systems > Cartesian 1 to Rotor CS.
To define the rotation motion:
  1. Right-click the Tools > Motions node and and select New > Rotation.
  2. Select the Rotation node and set Managed Coordinate Systems to Laboratory > Rotor CS. Check that Coordinate System is set to Laboratory.
  3. Select Rotation > Rotation Rate node and set Rotation Rate to ${Xrotor1_speed}.

    ${Xrotor1_speed} is a predefined parameter in the starting simulation that specifies a constant rotation rate of 109.12 rad/s.

  4. Select Rotation > Rotation Axis node and set Direction to [0.0, 0.0, 1.0].
To define the morphing motion:
  1. Right-click the Motions node and select New > Morphing.
  2. Select the Morphing node and set Morpher Method to BSpline.
The blade boundaries deform based on the total displacement, which has a rigid component (rotation) and a non-rigid component (the imported beam displacement). For such cases, you are advised to activate the Linear Fitter. With this option the morpher linearly approximates the rigid motion and performs the morphing calculation on the remaining blade deformation.
  1. Select the Morphing > BSpline Parameters node and activate Linear Fitter.
  2. Save the simulation.