CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

oxygen mass fraction in the flame area

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   November 7, 2013, 13:34
Default oxygen mass fraction in the flame area
  #1
Member
 
Roman
Join Date: Sep 2013
Posts: 81
Rep Power: 12
Roman1 is on a distinguished road
Hello. Please tell me if OF 2.2.1 has some dictionary inputs that sets the parameter like "oxygen mass fraction after burning reaction (oxygen index)"? The problem of my case is that the oxygen mass fraction near the burner and in all flame area is too high - 0.2 kg/kg. As a result the flame area is spread nearly all over fire compartment instead of looking like a small fire. I think you will agree that the oxygen mass fraction in the flame area must be about 0.05-0.1 kg/kg. My case is a slight modified fireFoam case from the tutorial. Thanks.
Roman1 is offline   Reply With Quote

Old   November 13, 2013, 04:07
Default
  #2
Member
 
Roman
Join Date: Sep 2013
Posts: 81
Rep Power: 12
Roman1 is on a distinguished road
The previous question was not sharp and correct. Sorry. I use a methane burner. Here are its parameters.

from file U:
fire
{
type fixedValue;
value uniform (0 0 0.17);
}
from file CH4:

fire
{
type fixedValue;
value uniform 1.0;
}

from file N2:
fire
{
type fixedValue;
value uniform 0.00;
}

from file T:
fire
{
type fixedValue;
value uniform 300;
}

from file p:
fire
{
type fixedValue;
value uniform 101325;

}

The square of "fire" is 1 m^2. Heat of reaction is 5.0e+7 (Dj/kg). So the power of the fire must be about Q= 0.17 * 1.23 (rho) * 5e+7 = 10455 kDj/s. Having such power the temperature above the burner must be about 1500 K and more. I have the temperature not more than 400 K. I steel need your help in resolving this problem, if possible, please.
Roman1 is offline   Reply With Quote

Old   November 13, 2013, 09:13
Default
  #3
Member
 
Roman
Join Date: Sep 2013
Posts: 81
Rep Power: 12
Roman1 is on a distinguished road
The thing was in BC for p_rgh. I was fixedValue. Changing it for fixedFluxPressure resolved the problem. Thanks to all and good luck.
Roman1 is offline   Reply With Quote

Reply


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
gradient of species mass fraction zhou FLUENT 1 March 14, 2020 07:55
Oxygen mass transfer lcea CFX 11 November 25, 2019 06:10
Non overlap area fractions saisanthoshm88 CFX 11 September 17, 2015 18:42
Mass Fraction and Mole Fraction don't tie up KieranHegarty FLUENT 1 February 28, 2015 10:22
Hydrogen + Air reaction, Oxygen mass fraction increases! CFD_Now FLUENT 0 October 8, 2012 01:14


All times are GMT -4. The time now is 19:40.