Study on turbulent burning velocity of outwardly propagating hydrogen-air flames with turbulence Karlovitz number

Outwardly propagating hydrogen-air turbulent flames were studied at the equivalence ratios from 0.6 to 1.0 and the initial pressures from 0.10 to 0.50 MPa. Turbulence intensity, u' was set to 0.80 to 1.59 m/s. The Markstein number decreased for increasing pressures and for small equivalence ratios. The ratios of turbulent to unstretched laminar burning velocities at a constant Peclet number increased with increasing turbulence Karlovitz number and decreasing Markstein number at a constant pressure. This ratio of burning velocities increased with increasing pressure at the equivalence ratios of 0.6 and 0.8. At the equivalence ratio of 1.0, however, it did not increase with increasing pressure although the Markstein number reduced with pressure.