Experimental study of laminar and turbulent spherical flame propagation characteristics of hydrogen-rich syngas

Abstract

Hydrogen-rich syngas, produced from biomass-based feedstocks, is a promising alternative energy source. However, its combustion characteristics are completely different from those of typical hydrocarbon fuels due to the presence of hydrogen. As a result, the kinetic mechanism of hydrogen-rich syngas premixed flame (HRSPF) propagation is very complex. In this work, the propagation of HRSPF was investigated employing different fan speeds (0–4273 rpm), hydrogen fractions (55%–95%), pressures (1.0 bar–3.0 bar), and equivalence ratios (0.6–1.0). It was found that the propagation speed of turbulent HRSPF increased when the mixing process of turbulent flow was enhanced or the stretching effect of flame front was weakened. When the turbulence intensity increased, the effect of flame inherent instability on the propagation speed of HRSPF was weakened. When the relative changes of thermal diffusion and mass diffusion of flame front were considerable, the effect of diffusional-thermal instability on flame acceleration process was more significant. On the contrary, the effect of hydrodynamic instability on flame acceleration process was more significant.