CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > CFX

Fan curves

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   January 15, 2013, 01:10
Default Fan curves
  #1
Senior Member
 
---------
Join Date: Oct 2010
Posts: 302
Rep Power: 8
saisanthoshm88 is on a distinguished road
Every fan manufacturer provides a fan curve with in the product manual but in reality the fan curve is different for different systems.

The manufacturer is completely unaware of the kind of system into which the fan shall be installed so in what ways is the fan curve provided by the manufacturer useful to the customer.

Could some one please provide a clarification on this.
__________________
Best regards,
Santhosh.
saisanthoshm88 is offline   Reply With Quote

Old   January 15, 2013, 12:32
Default
  #2
Senior Member
 
Edmund Singer P.E.
Join Date: Aug 2010
Location: Minneapolis, MN
Posts: 470
Rep Power: 10
singer1812 is on a distinguished road
Look up "Fan Laws" on google.....
singer1812 is offline   Reply With Quote

Old   January 16, 2013, 04:20
Default
  #3
Senior Member
 
---------
Join Date: Oct 2010
Posts: 302
Rep Power: 8
saisanthoshm88 is on a distinguished road
Fan laws as I'm aware of are only useful to predict the performance of a geometrically similar fan from the original fan curve.

But I'm talking about a situation where the actual system into which the fan is installed is physically different from the system in which the laboratory tests are performed by the manufacturer to get the fan curve.

Because as far as I know the fan curves are obtained by the manufacturer by testing the fan in a fully ducted condition and while in reality the fan shall operate in a totally different physical system so how is the fan curve provided by the manufacturer useful in that case.

As a CFD analyst my intention would be to use the fan curve in simulating the fan performance and not at all to have it as any selection criteria.
__________________
Best regards,
Santhosh.
saisanthoshm88 is offline   Reply With Quote

Old   January 16, 2013, 05:43
Default
  #4
New Member
 
Sainath
Join Date: Mar 2012
Posts: 27
Rep Power: 5
sainath.s@tdps.co.in is on a distinguished road
As I explained u earlier to the message, Do u have the load characteristics of the machine where you are going to install the fan?

Your point is valid that the fan is tested in a ducted channel and its characteristics will vary when placed inside the system.

You need to plot a similar curve for your machine. Super impose both the curves. The point at which the curves intersect is the operating point of the fan.

Also make considerations for the corrections that need to be done for the temperature and density because the manufacturer would have tested the fan at a particular temperature.
sainath.s@tdps.co.in is offline   Reply With Quote

Old   January 16, 2013, 10:35
Default
  #5
Senior Member
 
Edmund Singer P.E.
Join Date: Aug 2010
Location: Minneapolis, MN
Posts: 470
Rep Power: 10
singer1812 is on a distinguished road
If you are looking to select a fan, run your system at various flow rates.

You dont need a fan selected to do this, but perhaps you have a space claim that you want the fan to fit in, and with that model a good inlet and exit area (of the fan) that is similiar to a typical fan you might use (this will keep total pressure for the fan at approximately the same as the actual fan).

You can then map this total pressure system curve onto the any fan curve of your choice as Sainath said.

I dont think that this is a bad way of doing things, and will probably size your fan selection reasonably well.
singer1812 is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Simulation of Axial Fan Flow using A Momentum Source Subdomain Liam CFX 28 July 16, 2013 08:24
Considering the operating point instead of the fan curve saisanthoshm88 CFX 8 August 9, 2012 06:57
Jet fan and Tunnel simulation ahlo7 CFX 7 March 7, 2012 11:25
fan coefficients dhruv OpenFOAM 2 December 8, 2011 07:10
Propeller Fan Curve Simulation Teng_YJ FLUENT 2 February 16, 2009 20:37


All times are GMT -4. The time now is 05:17.