How to define fan performance curve in CFX using interpolation function?

atulpat · December 26, 2013, 02:49

Hello friends...
I am working on HVAC analysis of data center and I have fan performance curve. But I dont know how to define fan performance curve in CFX using interpolation function. Please help me.

Thanks in advance.

ghorrocks · December 26, 2013, 05:16

How are you trying to implement the fan? As a inlet or outlet, a source term or something else?

atulpat · December 26, 2013, 08:20

Yet I have not tried but little bit I know that we can implement it at inlet using sub-domain.

ghorrocks · December 27, 2013, 05:28

You implement it at an inlet OR a sub-domain. You should not do both. You can define an inlet to follow a fan curve, or define a momentum source on a sub-domain to follow a fan curve.

atulpat · December 28, 2013, 01:48

Thanks Ghorrocks.
Yes you are right. I already worked on data center using sub-domain and it is valid only when air flow from tile is directly going into the respective server rack (i.e. tile exactly located in front of server rack and air flow directly going into server rack). I used following expression for the same case for air flow in +ve X direction
Expression for RACKFAN

massFlow()@REGION:Tile1 / ((1.2 [kg m^-3])*area()@REGION:S_INLET)
and momentum source is

-1E5 [kg m^-3 s^-1]*(u- RACKFAN)

But in most of the cases it is not like that. Hence I am thinking to use Fan performance curve and it is possible to use the curve only by interpolation function. Please help me how we can use this interpolation function. I never used interpolation function that's why I came across this problem.

regards
Atul

ghorrocks · December 28, 2013, 05:46

The tutorials give examples of interpolation functions (nt sure which one though). Alternately just inset an interpolation object and stick in a few points to see how it works. They are quite simple to use.

atulpat · January 1, 2014, 08:42

Thanks ghorrocks
If you knows any tutorials then please provide me the links.

December 26, 2013, 02:49	How to define fan performance curve in CFX using interpolation function?	#1
atulpat New Member Atul Patil Join Date: Jul 2013 Location: India Posts: 26 Rep Power: 13	Hello friends... I am working on HVAC analysis of data center and I have fan performance curve. But I dont know how to define fan performance curve in CFX using interpolation function. Please help me. Thanks in advance.

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December 26, 2013, 05:16		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	How are you trying to implement the fan? As a inlet or outlet, a source term or something else?

December 26, 2013, 08:20		#3
atulpat New Member Atul Patil Join Date: Jul 2013 Location: India Posts: 26 Rep Power: 13	Yet I have not tried but little bit I know that we can implement it at inlet using sub-domain.

December 27, 2013, 05:28		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	You implement it at an inlet OR a sub-domain. You should not do both. You can define an inlet to follow a fan curve, or define a momentum source on a sub-domain to follow a fan curve.

December 28, 2013, 01:48		#5
atulpat New Member Atul Patil Join Date: Jul 2013 Location: India Posts: 26 Rep Power: 13	Thanks Ghorrocks. Yes you are right. I already worked on data center using sub-domain and it is valid only when air flow from tile is directly going into the respective server rack (i.e. tile exactly located in front of server rack and air flow directly going into server rack). I used following expression for the same case for air flow in +ve X direction Expression for RACKFAN massFlow()@REGION:Tile1 / ((1.2 [kg m^-3])area()@REGION:S_INLET) and momentum source is -1E5 [kg m^-3 s^-1](u- RACKFAN) But in most of the cases it is not like that. Hence I am thinking to use Fan performance curve and it is possible to use the curve only by interpolation function. Please help me how we can use this interpolation function. I never used interpolation function that's why I came across this problem. regards Atul

December 28, 2013, 05:46		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	The tutorials give examples of interpolation functions (nt sure which one though). Alternately just inset an interpolation object and stick in a few points to see how it works. They are quite simple to use.

January 1, 2014, 08:42		#7
atulpat New Member Atul Patil Join Date: Jul 2013 Location: India Posts: 26 Rep Power: 13	Thanks ghorrocks If you knows any tutorials then please provide me the links.