variavel0=<b>Guenther Carlos Krieger</b> - guenther@usp.br Universidade de São Paulo
<b>Abstract.</b> A non-premixed turbulent methane flame is investigated in this work. Special emphasis is given to the local extinction phenomena. The numerical simulation is performed with PDF method enhanced with the algorithm "in situ adaptative tabulation" (ISAT). The chemistry is described by a reduced mechanism with 10 global reactions and 14 species. The ISAT method avoids both, the memory consuming look-up table, and the time consuming integration fo differential equations of the chemical reactions. The coupling between thermo-chemistry and turbulence models is done using a PDF-Method and a conventional CFD code. The flame structure is investigated by means of average value and conditioned average values of temperature and carbon monoxide (CO) concentration. The numerical results are compared with experimental data. It is verified that the profiels of averaged quantities such as mixture fraction, temperature and major species concentrations and carbone monoxide are in acceptable agreement with the experimental data. Beside the mean value of temperature and mass fraction of CO, conditioned mean values are also presented. It can be seen that partial extinction is very pronounced in the near nozzle region, where Damkohler Number is low. It is very important to mention that such insight of the flame is only possible using the PDF Method and detailed chemistry, which is feasible with the ISAT algorithm. Moreover, the resulting algorithm proved to be up to 16 times faster then the usual PDF approach. Therefore, in the overall picture this method allows for a better modeling of the whole combustion process.
<b>Keywords.</b> Combustion, Extinction, Nom-premixed, Turbulence, Methane.