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Old   December 19, 2013, 20:57
Default Modelling Impulse Fans
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Michael Smith
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Hi all,

I've been trying for a while to model an impulse fan correctly.

If I specify the suction side of the fan as an exhaust and the supply side as an inlet, I get pretty good flow patterns, however the air properties (such as age of air) are not preserved.

How do I link the two boundaries to preserve conditions?
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Old   December 20, 2013, 05:12
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Glenn Horrocks
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Use a momentum source rather than an inlet/outlet pair. If you want to be tricky you can also define it to have the fan performance curve.
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Old   January 5, 2014, 19:07
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Michael Smith
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Hi Glenn,

Thanks for the reply.

I have tried that, but it doesn't seem to want to converge (and the results look pretty off). Are there other specific settings that I should be focusing on to assist?

Cheers,
Mike
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Old   January 5, 2014, 19:08
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Michael Smith
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Also, I think the use of a momentum source requires specific geometry setup, ie, there isn't two separate bodies/domains, but one domain and a subdomain, or something...? I'm not 100% across how to set it up
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Old   January 12, 2014, 07:13
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A momentum source is the normal way to do this. If it is not working for you then you have not set it up correctly.

I do not understand you comment "two separate bodies/domains". You just define the fan region as a subdomain with the source applied to it.
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Old   January 13, 2014, 18:09
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Edmund Singer P.E.
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Are you setting your age of air at the "outlet of the fan" equal to the age of air at "inlet of fan"?

Of course, using a momentum source will not require this. But if you kept it as a inlet/outlet pair, you will need to do this in order to maintain the correct age.
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Old   January 29, 2014, 18:49
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Michael Smith
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I'm not sure how to do that sorry, re setting the outlet value equal to the inlet value. Quick research suggested it needed some coding that was more complex than my experience could deal with
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Old   January 29, 2014, 18:49
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Ah, the issue was that in SpaceClaim you can't seem to set multi-body parts by creating a new part as you can in DesignModeller for compatable meshing...
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