modelFriction
Extends from Machines.Interfaces.FlangeSupport (Shaft and support), Modelica.Thermal.HeatTransfer.Interfaces.PartialElementaryConditionalHeatPortWithoutT (Partial model to include a conditional HeatPort in order to dissipate losses, used for textual modeling, i.e., for elementary models).
Information
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 |
See also
If it is desired to neglect friction losses, set frictionParameters.PRef = 0 (this is the default).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| FrictionParameters | frictionParameters | Friction loss parameters | |
| Boolean | useHeatPort (from PartialElementaryConditionalHeatPortWithoutT) | false | = true, if heatPort is enabled |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Mechanics.Rotational.Interfaces.Flange_a | flange (from FlangeSupport) | Shaft end | |
| Modelica.Mechanics.Rotational.Interfaces.Flange_a | support (from FlangeSupport) | Housing and support | |
| HeatTransfer.Interfaces.HeatPort_a | heatPort (from PartialElementaryConditionalHeatPortWithoutT) | Optional port to which dissipated losses are transported in form of heat |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| SI.Angle | phi (from FlangeSupport) | Angle between shaft and support | |
| SI.Torque | tau (from FlangeSupport) | Torque | |
| SI.AngularVelocity | w (from FlangeSupport) | Relative angular velocity of flange and support | |
| SI.Power | lossPower (from PartialElementaryConditionalHeatPortWithoutT) | Loss power leaving component via heatPort (> 0, if heat is flowing out of component) |