Authors: B Prabasena M Röder T Kathrotia U Riedel T Dreier C Schulz
Publish Date: 2012/03/30
Volume: 107, Issue: 3, Pages: 561-569
Abstract
A detailed comparison has been conducted between chemiluminescence CL species profiles of OH∗ CH∗ and C2 ∗ obtained experimentally and from detailed flame kinetics modeling respectively of atmospheric pressure nonpremixed flames formed in the forward stagnation region of a fuel flow ejected from a porous cylinder and an air counterflow Both pure methane and mixtures of methane with hydrogen between 10 and 30 by volume were used as fuels By varying the airflow velocities methane flames were operated at strain rates between 100 and 350 s−1 while for methane/hydrogen flames the strain rate was fixed at 200 s−1 Spatial profiles perpendicular to the flame front were extracted from spectrograms recorded with a spectrometer/CCD camera system and evaluating each spectral band individually Flame kinetics modeling was accomplished with an inhouse chemical mechanism including C1–C4 chemistry as well as elementary steps for the formation removal and electronic quenching of all measured active species In the CH4/air flames experiments and model results agree with respect to trends in profile peak intensity and position For the CH4/H2/air flames with increasing H2 content in the fuel the experimental CL peak intensities decrease slightly and their peak positions shift towards the fuel side while for the model the drop in mole fraction is much stronger and the peak positions move closer to the fuel side For both fuel compositions the modeled profiles peak closer to the fuel side than in the experiments The discrepancies can only partly be attributed to the limited attainable spatial resolution but may also necessitate revised reaction mechanisms for predicting CL species in this type of flame
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