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Abstract
The axisymmetric Navier-Stokes model together with detailed chemical kinetics and variable transport properties has been applied to analyze the effects of the multidimensional flow on the flame characteristics in the nitrogen-diluted hydrogen counterflow nonpremixed flame. Computations are carried out for the laminar counterflow hydrogen-air flames with two fuel dilutions. In order to investigate the effects of the jet exit velocity profiles on the hydrogen-air diffusion flame structure, computations are made for two boundary conditions simulating the plug-flow and parabolic-flow velocity profiles at nozzle exit. In case of the highly diluted hydrogen flames, the near-extinction flame structure and extinction flame process are numerically studied for two nozzle exit area-averaged velocities based on the plug-flow profile. Numerical results indicate that the jet exit profiles significantly influence the flame structure in terms of strain rate, flame thickness, peak temperature, overlap of fuel and air, and differential diffusion. Effects of multidimensional flow and strain rate on the near-extinction structure of the highly diluted hydrogen flames are also discussed in detail.
