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AeroSim Blockset User’s Guide
4.3.2
Background Wind
The block computes the background wind velocity components in
body axes. It is represented in Fig. 46.
Figure 46: Background Wind Block
Block characteristics:
1. Parameters: none.
2. Inputs:
• WindsNED = the [3×1] background wind velocity components in inertial frame (North-East-Down).
• DCM = the [3 × 3] direction cosine matrix for inertialto-body transformation.
3. Outputs:
• WindVel = the [3 × 1] wind velocity components in
body axes.
• WindAcc = the [3 × 1] wind acceleration components
in body axes.
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BLOCK REFERENCE
4. Details: The block is applying a frame transformation from
inertial (geographic) to body frame, using the rotation matrix provided. The numerical time derivative of the resulting
velocity vector is then computed. This captures the effect of
time-varying background wind which can be encountered in
some weather conditions (wind shear, thermals, cyclones).
5. Usage: The input to this block can be provided as a constant, or from a weather model. The outputs of this block is
used by the Wind Force, Turbulence, Wind Shear blocks in
Atmosphere model, and by Wind-axes Velocities in Aerodynamics.