The Relationship of the Laminar Flame Width to Flame Speed

Abstract The width ( δ ) of a laminar flame is often characterized as a basic property of the flame and is sometimes used in turbulent combustion models to categorize the turbulence scale of the mixture. From computed flame speeds and temperature profiles of C3H8/Oa/Ns (o=1) flames we have determined widths, using definitions based on ( dT*sol;dx)max, Q (the heat release rate) and r (the characteristic chemical time) and characteristic distances have been determined from the transport properties of the burned (δ b) and unburned (δ u) gases. The flame widths are compared via the transport properties, (A/Cp), of the gas mixtures in the flame where A is the thermal conductivity and Cp is the heat capacity. A derived or approximate transport property for the flame widths is defined by the product of the mass flow rate (Mƒ) and the flame width. The functional dependence of these flame widths is compared by varying the Na fraction and initial mixture temperature. Both the set of Na fractions and mixture tempera...

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