Hello, everyone, First many thanks for versi and jdc's help. Last time I post a question about mixture fraction. At that time I did not describe the problem clearly, I beg your pardon. I want to simulate a diffusion flame with irrreversible infinite fast chemical approximation. So I think I can get the temperature and mass fraction only from the mixtrue fraction Z;

Z=(f-f_ox)/(f_fu-f_ox), f=s*Y_fu-Y_ox; where Y_fu, Y_ox is mass fraction of the fuel and oxidizer.

In the book "Theoretical and Numerical Combustion" ( edited by Thierry P and Denis V , 2001, R.T. Edwards, Inc. ),I find the formular from Z to calculate temperature (page93). Am I right? Thanks again!

Hi Sheng,

Page 93 is indeed giving you relations Z-> T, Fuel, Oxid and Product. Note: this relation also assume that all species and energy are diffusing with the same coefficient (Lewis = 1 for all all species).

The problem will be in determining Q and Cp!

Good luck. Julien