Preheat and reaction zones thickness of stratified premixed flames generated by industrial injector

Burning area of stratified and fully premixed turbulent flames stabilized on an industrial gas turbine burner prototypewere investigated experimentally at ambient conditions. Hot-wire anemometry technique was used to characterize the background turbulent flow. The Rayleigh scattering measurement was conducted to quantify the mixedness fields as well as the flame burning area. Mean bulk flow velocities ranging from 5 to 50 m/s were tested for non-reacting conditions. At 50 m/s, only the stratified flames were stabilized, and as a result, the flames were tested for mean bulk flow velocities up to 45 m/s. The global fuel-air equivalence ratio was set to unity. The hot-wire anemometry results show that there exists a hydrodynamic instability near the lobes of the injector, which is mostly pronounced at the largest tested mean bulk flow velocity. The mixedness calculations suggest that, for mean bulk flow velocities smaller than 25 m/s, the stratification is negligible; however, non-homogeneous distribution of the fuel is observed for larger mean bulk flow velocities. The PDF of the flame temperature divided by the normalized mixture Rayleigh scattering cross section was used to estimate the flame burning area. It was shown that stratification increases this parameter. This conclusion extends our previous findings to mean bulk flow velocities that are more relevant for industrial applications.