Numerical analysis of quenching distance in laminar premixed hydrogen and methane flames

The quenching behavior of laminar premixed hydrogen-air and methane-air flames is studied in two-dimensional configurations with detailed chemistry. Quenching distances are determined by simulating an initially stationary flame and then decreasing the inlet speed, allowing upstream flame propagation in a converging duct. The quenching distance is then defined as the distance between the cold surfaces where the flame extinguishes due to heat loss to the walls. The results for methane-air and hydrogen-air mixtures at various equivalence ratios are compared with experimental data, showing good agreement. The effects of flow inlet velocity, geometry, and wall temperature on quenching distance are investigated. The quenching distance is found to be sensitive to the inlet speed and decreases with decreasing inlet speed. The quenching distance is shown to decrease linearly with increasing wall temperature in hydrogen-air flames. In addition, the quenching distance depends on the geometry of the setup. Slit and annular ducts result in similar quenching distances, whereas circular ducts have higher quenching distances compared to the others. The study highlights the importance of considering these factors in burner design and flashback prevention devices.