The action of sodium bicarbonate and of silica powder on upward propagating flame in a vertical duct

The effect of NaHCO 3 and SiO 2 powders, freely falling under gravity, on a flame propagating upward in a lean methane-air mixture, has been studied in a vertical duct for various powder concentrations and mean particle sizes. At low concentrations both powders produce an increase in the flame propagation rate and the flame front temperature, due probably to aerodynamic factors. At higher concentrations the two powders behave differently, both quantitatively and qualititatively. The results suggest that while both powders produce aerodynamic and thermal effects, NaHCO 3 also acts chemically.