Experimental and numerical investigation of laminar hydrogen-air counterflow diffusion flames

Flame structure measurements, made using UV Raman scattering and OH laser induced predissociative fluorescence (LIPF), are compared to one dimensional (1D) numerical simulations. Three low stretch (far from extinction) flame conditions are measured: 1) 20% H-2 + 80% N-2 vs. air, a = 133 s(-1); 2) 50% H-2 + 50% N-2 vs. air, a = 125 s(-1); 3) 100% H-2 vs. air, a = 100 s(-1). Comparisons of major species measurements with the 1D simulations are in excellent agreement for all cases. Measurements of OH in the 100% H-2 flame are slightly lower than the numerical predictions. However, considering spatial averaging and measurement uncertainty due to OH calibration, the OH measurements are in good agreement with the numerical simulations. Mixture fraction measurements (based on atomic nitrogen and atomic hydrogen) agree with the numerical simulations and indicate that differential diffusion effects are important in flames where the primary reaction zone is in a region of low convective velocity (e.g., the vicinity of the stagnation plane).