Uniform pressue increase over fan

alxe · August 30, 2011, 01:32

Hi!

I'm modeling a closed-circiut windtunnel in ANSYS CFX v13 and am using an interface in CFX-Pre to simulate the fan in the tunnel. I.e I have ha fluid fluid interface with general connection between the two adjacent faces that is supposed to be the fan. Under "Additional Interface Models" I've selected Conservative Interface Flux and a pressure change of 450 Pa. In this simulation I'll neglect the vortices caused by the fan so I want a uniform flow out of the fan.

My problem is that when I do it this way I get a pressure gradient in the cross section of the fan since the flow before the fan isn't uniform and the interface just increases the pressure at each point by 450 Pa (I guess?). Does anyone have any idea about how I can make the flow out of the fan uniform?

Thanks!

ghorrocks · August 30, 2011, 06:23

Why not just use a velocity inlet and a pressure outlet? Then everything is much easier.

alxe · August 30, 2011, 06:39

Quote:

Originally Posted by ghorrocks

Why not just use a velocity inlet and a pressure outlet? Then everything is much easier.

I tried that first but I don't want a hole in my tunnel which I seemed to need to do as you say.

ghorrocks · August 30, 2011, 06:49

The only reason you would link it up is because the inflow to the fan affects the outflow somehow - but as you say you want an even pressure that does not seem the case. So do not link it but define it separately and things will be much easier.

alxe · August 30, 2011, 19:15

Quote:

Originally Posted by ghorrocks

The only reason you would link it up is because the inflow to the fan affects the outflow somehow - but as you say you want an even pressure that does not seem the case. So do not link it but define it separately and things will be much easier.

You're probably right. I'll try do it that way again. Thanks!

August 30, 2011, 01:32	Uniform pressue increase over fan	#1
alxe New Member Alexander Join Date: Aug 2011 Posts: 8 Rep Power: 14	Hi! I'm modeling a closed-circiut windtunnel in ANSYS CFX v13 and am using an interface in CFX-Pre to simulate the fan in the tunnel. I.e I have ha fluid fluid interface with general connection between the two adjacent faces that is supposed to be the fan. Under "Additional Interface Models" I've selected Conservative Interface Flux and a pressure change of 450 Pa. In this simulation I'll neglect the vortices caused by the fan so I want a uniform flow out of the fan. My problem is that when I do it this way I get a pressure gradient in the cross section of the fan since the flow before the fan isn't uniform and the interface just increases the pressure at each point by 450 Pa (I guess?). Does anyone have any idea about how I can make the flow out of the fan uniform? Thanks!

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August 30, 2011, 06:23		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Why not just use a velocity inlet and a pressure outlet? Then everything is much easier.

August 30, 2011, 06:49		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	The only reason you would link it up is because the inflow to the fan affects the outflow somehow - but as you say you want an even pressure that does not seem the case. So do not link it but define it separately and things will be much easier.