Learning Forum

[cunyi.ji]

Hello,

How is it possible to model the forced convection due rotation of the rotor of an electric motor (outer rotor BLDC)?
It can be approximations.



Regards,

[Iceman]

Thanks for asking questions on Forum. You can use an Air Hollow Cylinder to enclose the rotating part, then apply MRF to the Hollow Cylinder. Please check our training material about Special Application: Advanced Fan Modeling on Ansys Learning Hub (https://learninghub.ansys.com/learn/courses/319/ansys-icepak-in-ansys-electronics-desktop-advanced). Thanks.

[cunyi.ji]

Thank you for your answer.

Which total power should I consider - how do I know which value should I input?

[Iceman]

The hollow cylinder should have lower meshing priority than the rotating solids. There is no need to input power for the air block BC as air doesn't generate heat. It is only used to apply MRF with proper RPM to make the air around rotating objects to rotate.

[Iceman]

If you are doing conduction only, please check AEDT Mechanical which has Rotating Fluid boundary for motor applications. Thanks.

[cunyi.ji]

Thanks for the suggestion.
Since the convection is only considered with Heat Transfer Coefficient, which will be calculated using empirical equations, how accurate will be the results?

[Iceman]

The rotating fluid BC is applied to the gap between rotor and stator. For the exterior surface of rotor, you can apply a uniform HTC or a non uniform HTC mapped from Icepak. The uniform HTC will be less accurate but is very easy to set up.

[Iceman]

The rotating bc can account for both conduction and convection of air in the gap between rotor and stator.

[Iceman]

Please check our AEDT Mechanical trainng material on Ansys learning hub if you are interested in this approach. Thanks.