Turbulent flame speed for hydrogen-rich fuel gases at gas turbine relevant conditions

In this paper, correlations of the global consumption-based turbulent flame speed (ST) for hydrogen-rich fuel gases are presented. Interpretations on the derived ST are supplemented by a fractal analysis of the flame front. The findings are based on an experimental investigation of lean-premixed, dump-stabilized axisymmetric flames at gas turbine conditions (preheated up to 623 K and pressurized up to 2.0 MPa). Depending on the turbulent Damköhler number (Da), distinct characteristics of a normalized turbulent flame speed, ST/SL0, are observed (SL0is the unstretched laminar flame speed). While the dependence of ST/SL0 on the turbulent Reynolds number (ReT) is revealed for the flames with fast chemistry (Da > 1), flame stretch becomes dominant in determining ST/SL0 for those with slow chemistry (Da < 1). The transition from flame front wrinkling to flame stretch as the dominant factor is also evidenced by the fractal characteristics of the flame front.