Typical Setup of Rotating Domain, Rotational Continuity Pair, and Rotational Periodicity
In Figure 5-6 and Figure 5-7 it is shown how typical conditions should be set for a rotating machine where either the full machine or a sector is drawn in the geometry. For the sake of simplicity, a synchronous machine with an external stator and an internal rotor with 10 poles is used in this example. Furthermore, the stator configuration is such that the minimal sector corresponds to one fifth of the whole geometry.
In this example, the features that should be added in both cases are as follows:
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The region inside of the cyan line should have a different Rotating Domain node, with Time periodic rotation set to either Synchronous (pole pair) or User defined so that αTP = 4π/npoles = 72°.
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The cyan and red lines correspond to the source and destination selections for the pair where the Rotational Continuity Pair feature should be applied.
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For such a pair, the source and destination should be either full circles or integer fractions of one. If an integer fraction is defined, a variable is introduced for the number of sectors that make up the full machine.
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Both the source and the destination should be adjacent to only one single geometry component.
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Multiple Rotational Continuity Pair nodes are allowed for modeling machines with multiple rotors.
Figure 5-6: Regions where different features need to be applied for rotating motion, in the case where the full machine is modeled.
If a sector of the whole machine is drawn, a Rotational Periodicity node should also be added with a selection corresponding to the green line in Figure 5-7.
When modeling a single sector, it is important to specify if the symmetry is periodic or antiperiodic. If the Rotational periodicity type is set to From physics, this is done by specifying the Number of poles in the Motion Settings section at the physics level. If the number of poles is an even multiple of the detected number of sectors, continuity is assumed. Conversely, if the number of poles is an odd multiple of the detected number of sectors, antiperiodicity is going to be assumed. The number of detected sectors is displayed along with the type of periodicity in the bottom of the Motion Settings section. The default value of the number of poles is zero, which results in periodicity being assumed.
Figure 5-7: Regions where different features need to be applied for rotating motion, in the case where a single sector of the machine is modeled.
The button Add Rotational Boundary Features in the Motion Settings section automatically adds one Rotational Continuity Pair node for each pair that is geometrically consistent with two circular sliding objects. It also adds the corresponding Rotational Continuity Pair node if a single sector is drawn.