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

Simulation of Axial Fan Flow using A Momentum Source Subdomain

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

Reply
 
LinkBack Thread Tools Display Modes
Old   March 15, 2013, 07:01
Default
  #21
New Member
 
Join Date: Feb 2013
Posts: 4
Rep Power: 4
klettmann is on a distinguished road
Hello philflow,

have you written an FAQ or a short summary of your experience with an axial fan simulation? I'm working on the same problem. It would be very nice if you have something like an summary for me!

Best regards,

A.
klettmann is offline   Reply With Quote

Old   March 16, 2013, 05:59
Default
  #22
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,824
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
The documentation describes source terms and source term coefficients pretty well.
ghorrocks is offline   Reply With Quote

Old   April 18, 2013, 04:00
Default
  #23
New Member
 
Join Date: Feb 2013
Posts: 4
Rep Power: 4
klettmann is on a distinguished road
Hello again,

I have problems to simulate an axial fan. In the image, the test case I am working with is shown. The green bar, is my subdomain.

I am able to set a momentum source to get the exact pressure rise. But this is only half the way I have to go.

I would like to set a specific pressure rise and a volumeflow rate.
My idea is to simulate different blades in my fan. the first blade has an pressure rise of 35[kPa] and a volume rate of 70 [m^3/s] the second one has a pressure rise of 35 [kPa] and a volumeflow rate of 50[m^3/s]. So in my opinion the subdomain is a "black box" for my blades. And I am able to simulate different blades.

I have tried a lot of possibilities.
1.I rotate the subdomain with the frame change model "stage" and give a axial momentum source
2.I try to give an axial and a theta momentum source
3. I give an axial momentum source and an energy sourc


I have no more real ideas how to simulate different blades in my nacelle.
I hope someone can help me.
Thanks a lot.
klettmann is offline   Reply With Quote

Old   April 18, 2013, 04:06
Default
  #24
New Member
 
Join Date: Feb 2013
Posts: 4
Rep Power: 4
klettmann is on a distinguished road
here is the image
http://www.flickr.com/photos/95041584@N02/8660319970/
klettmann is offline   Reply With Quote

Old   April 18, 2013, 06:29
Default
  #25
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,824
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
I think you will find that specifying the pressure rise and flow rate is over-specifying the flow. You specify either the pressure rise or the flow rate but not both. You can even specify the pressure rise as a function of flow rate (or vice-versa) - in fact the is recommended if you are trying to find the operating point and you do not know the exact fan speed.
ghorrocks is offline   Reply With Quote

Old   April 23, 2013, 10:04
Default
  #26
New Member
 
Join Date: Feb 2013
Posts: 4
Rep Power: 4
klettmann is on a distinguished road
Is there no way to specify both parameters? In my thougths it is like I have two different Operating Points which I can define. Or like two different blades.
Blade 1: pressure difference 35 [kPa] with 70 [m^3 s^-1]
Blade 2: pressure difference 35 [kPa] with 60 [m^3 s^-1]

With only the Momentum Source I can give a pressure change and a result is a volumeflow rate.
The task of my simulation is to find solutions for my nacelle with different blades.
klettmann is offline   Reply With Quote

Old   April 23, 2013, 16:37
Default
  #27
Senior Member
 
Edmund Singer P.E.
Join Date: Aug 2010
Location: Minneapolis, MN
Posts: 494
Rep Power: 10
singer1812 is on a distinguished road
Glenn is correct. You are overspecifying the problem. I assume your blades have more than one operating point. You should have a mdot vs Pdrop for each blade.

You can input this into your model, and your model will find the operating point using the Pdrop of your system.
singer1812 is offline   Reply With Quote

Old   July 16, 2013, 07:11
Default Momentum source for cylinder in FLUENT
  #28
New Member
 
Hanumanth
Join Date: Aug 2009
Posts: 6
Rep Power: 7
p08tm007 is on a distinguished road
In fluent there is only possibility of defining momentum source in either x,y & z directions. If we want to define momentum source over a cylinder, then how to do this in fluent. Hey guys please help me regarding this, as this option is not there in fluent.

Thanks in Advance...
p08tm007 is offline   Reply With Quote

Old   July 16, 2013, 08:24
Default
  #29
Senior Member
 
Edmund Singer P.E.
Join Date: Aug 2010
Location: Minneapolis, MN
Posts: 494
Rep Power: 10
singer1812 is on a distinguished road
This is a CFX forum. Try Fluent Forum.

But with not much thought put into the answer, you could use a coordinate transform to put your source into cartesian coords.
singer1812 is offline   Reply With Quote

Reply

Tags
axial, fan, momentum source, subdomains

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
Axial fan simulation in UG/NX 7.5 fan123 Main CFD Forum 2 April 23, 2011 08:22
OpenFOAM on MinGW crosscompiler hosted on Linux allenzhao OpenFOAM Installation 127 January 30, 2009 20:08
flow simulation across a small fan jane luo Main CFD Forum 15 April 12, 2004 17:49
Modeling a fan with a momentum source Pascale Fonteijn CFX 2 November 21, 2002 17:33
Question concerning about the flow simulation of a fan in an engine room. ghlee Main CFD Forum 3 October 21, 1998 07:05


All times are GMT -4. The time now is 09:22.