# oxygen mass fraction in the flame area

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 November 7, 2013, 14:34 oxygen mass fraction in the flame area #1 Member   Roman Join Date: Sep 2013 Posts: 45 Rep Power: 5 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.

 November 13, 2013, 05:07 #2 Member   Roman Join Date: Sep 2013 Posts: 45 Rep Power: 5 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.

 November 13, 2013, 10:13 #3 Member   Roman Join Date: Sep 2013 Posts: 45 Rep Power: 5 The thing was in BC for p_rgh. I was fixedValue. Changing it for fixedFluxPressure resolved the problem. Thanks to all and good luck.

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