Through Ventilation Cooling
Description
This document gives a brief description of how to set up a Motor-CAD model for a through
ventilated machine. The Motor-CAD model allows the cooling fluid to be passed down the
airgap, stator and rotor ducts.
Setting the housing type and stator ducts
The housing type should be set up to be that of the modeled machine as shown below.
The number and size of the stator ducts can be set using the parameters shown below.
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Setting the rotor ducts
The rotor ducts can be set up as shown below:
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Setting the machine losses
The losses of the machine are defined in the losses page as shown below. The default
losses are used in this example. There are different loss models allowing for the losses to
vary with speed, temperature and load.
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Setting the machine cooling
The machine cooling is setup as shown below.
The Through Ventilation option must be selected.
The cooling type on the exterior of the housing is specified using the Cooling Type option:

Natural Convection = only natural convection and radiation from outside of machine
(Totally Enclosed Non Ventilated - TENV).

Blown Over = air/ fluid is blown over outside of machine. (Totally Enclosed FanCooled - TEFC).
The External fluid is the fluid on the outside of the machine. The internal fluid is the fluid
blown through the machine.
The fluids and their properties can be created and edited in the fluid data base (Input Data>Material Properties->Fluids).
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The through ventilation flow type is defined by selecting one of the options shown below:

Blower (Constant flow rate) = Constant flow rate through machine from external fan,
flow rate specified directly by user

Blower (Constant flow rate from Fan Characterisitic) = Constant flow rate through
machine from external fan, flow rate calculate by Motor-CAD from fan characteristic

Shaft mounted fan (flow rate proportional to speed) = Fan is mounted on shaft and
flow rate will vary proportionally with speed of shaft

Shaft mounted fan (user specified flow rate variation) = Fan is mounted on shaft and
flow rate will vary with speed of shaft as defined by user
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The inlet and outlets and flow direction are also specified as shown below. Have also
changed the inlet type and number of holes to 30 for this design:
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The flow paths can then be seen in the cross section views to check that the cooling paths
have been set up correctly.
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The flow rates, flow resistances and velocities calculated for the through ventilation fluid flow
are shown below. The flow rates through the rotor, stator and airgap are highlighted below.
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The heat transfer coefficients are shown below. The the axial h values (due to fluid flow) and
rotational h values of the end space model are combined when calculating the h values.
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The Endspace h value model and calculation details are shown in input Data->End space as
shown below. These h values are used in the through ventilation h value calculation.
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If required the endspace rotational effects can be ignored in the through ventilation
calculation by deselecting the option shown below.
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Viewing the results
The power removed from the machine by the through ventilation in stator, rotor and airgap is
shown in the steady state schematic.
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The node temperatures can also be viewed on the radial and axial cross sections as shown
below.
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The through ventilation fluid temperatures are shown in the output data sheet as shown
below.
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Transient Analysis
Transient analysis can also be performed on this model. Full details of the transient analysis
options and method of calculation are given in the transient analysis tutorial.
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