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

ejector for purging system of fired furncae

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   November 28, 2018, 12:10
Default ejector for purging system of fired furncae
  #1
Member
 
wadoud
Join Date: Nov 2010
Posts: 67
Rep Power: 12
wadoud31 is on a distinguished road
Hi all,

I am trying to simulate an existing device(ejector) used to purge an fired furnace, but the issue is how we must define the boundary conditions.
I tried the boundary conditions below:
Reference pressure: 1 atm
Inlet of ejector: static pressure 7 bar and velocity 48 m/s
In the bottom of the furnace I tried 2 options:
1 inlet of furnace with a static pressure 0 atm
2 as opening with a static pressure 0atm
Out of the furnace I tried 2 options:
1 outlet of furnace with a static pressure 0 atm
2 as opening with a static pressure 0atm
The simulation did not converge.
NB: the geometry and the conditions is like the site (real case).
I need your help and your advice; thank you in advance.


best regards,
Attached Images
File Type: jpg furnace.jpg (25.8 KB, 11 views)
File Type: jpg ejector.jpg (44.1 KB, 11 views)
File Type: png cfx.png (27.5 KB, 10 views)
File Type: png ANSYS CFX Solver.png (34.9 KB, 8 views)
wadoud31 is offline   Reply With Quote

Old   November 29, 2018, 12:28
Default
  #2
Member
 
wadoud
Join Date: Nov 2010
Posts: 67
Rep Power: 12
wadoud31 is on a distinguished road
Hi all,

after trying a lot of different setups, it seems that I need some help with the boundary conditions of my problem. I'm looking for a stable (steady state?) solution
I am using ANSYS CFX 14.5.
thanks, I am very grateful
wadoud31 is offline   Reply With Quote

Old   November 29, 2018, 19:45
Default
  #3
Senior Member
 
Join Date: Dec 2017
Posts: 150
Rep Power: 4
AliE is on a distinguished road
Hi, since nobody is replying, I will attempt an answer for this.

First of all you should post you question in cfx section here in cfd-online forum. Somebody skilled with the software can be helpful.

In my opinion your problem is that you are trying to fix both the pressure and the velocity at inlet. Up to my knowledge you can do 3 things:
-specify the velocity and leave the pressure free to adjust using zero gradient (known as velocity inlet)
- fix the pressure and the velocity direction (not the magnitude), in this case velocity will be calculated in response to the pressure assigned
-fix the total pressure and the velocity direction

Try if one of these works for you.
AliE is offline   Reply With Quote

Old   December 1, 2018, 10:34
Default
  #4
Member
 
wadoud
Join Date: Nov 2010
Posts: 67
Rep Power: 12
wadoud31 is on a distinguished road
dear ALIE, thanks for your advice, I try this simulation to know the mass flow rate of air at the bottom in the furnace, I used the knonw boundary conditions wich are:
1 the speed, mass flow rate and the pressure at the inlet of the ejector.
2 at the bottom of the furmace (atmospheric openning), we have only the atmospheric pressur, normaly is the inlet of atmospheric air.
3 at th top (duct) of furnace is the same (atmospheric openning), normaly is the exit (out).
at the and of this simulation we must confirm the mass flow rate at the bottom;

thank you very much
wadoud31 is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Cooling system design with CFX, Mechanics and system coupling gmingardo CFX 12 December 2, 2016 15:26
Remeshing_ ANSYS 14.0_ System Coupling acdesa ANSYS 4 November 2, 2016 10:12
2way FSi, Initialize with steady solution, Fluent, Transient Sturcural, System Coupli mmkkeshavarzi FLUENT 0 June 22, 2016 09:26
In which coordinates system is expressed velocity malaboss OpenFOAM Post-Processing 2 April 18, 2013 07:00
System Build Advice for FEA cycleback Hardware 1 February 8, 2013 21:53


All times are GMT -4. The time now is 09:30.