Burning Times of Magnesium Ribbons in Various Atmospheres

摘要: Some details of the physical mechanism of the combustion of magnesium ribbon were investigated, and burning times for magnesium ribbons were determined with various mixtures of oxygen in argon, nitrogen, helium, and argon - water vapor. Evidence from this investigation indicates that a gas-phase rather than a surface reaction occurs, which bears some analogy to the combustion of liquid-fuel drops. The experimental burning times are compared with those calculated by using a vapor-phase heat- and mass-transfer mechanism. The infinitesimally thin flame frent concept successfully applied to fuel drops was abandoned in favor of a high-temperature reaction zone of finite thickness. Agreement between experimental and calculated values for burning time in terms of oxygen concentration for the argon- and nitrogen-inerted systems was quite satisfactory on a relative basis; actual numerical values agreed within a factor of 2 to 3. Agreement was less satisfactory for low-density helium-inerted atmospheres, although the changes observed experimentally were in the direction indicated by the calculation.