The friction losses are considered by the equations

   tau / tauRef = (+w / wRef) ^ power_w    for w > +wLinear
 - tau / tauRef = (-w / wRef) ^ power_w    for w < -wLinear


  tauRef * wRef = PRef

being the friction torque at the reference angular velocity wRef. The exponent power_w is approximately 1.5 for axial ventilation and approximately 2.0 for radial ventilation.

For stability reasons the friction torque tau is approximated by a linear curve

  tau / tauLinear = w / wLinear


  tauLinear = tauRef*(wLinear/wRef) ^ power_w

in the range -wLinear ≤ w ≤ wLinear with wLinear = 0.001 * wRef. The relationship of torque and angular velocity is depicted in Fig. 1

Fig. 1: Friction loss torque versus angular velocity for power_w = 2

See also


If it is desired to neglect friction losses, set frictionParameters.PRef = 0 (this is the default).

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