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