Radiation from Buoyant Turbulent Diffusion Flames

Abstract

The relationship between the radiant fraction, X _R, of the total heat release rate from buoyant turbulent diffusion flames and a fuel's laminar flame smoke point is refined and extended to include: additional hydrocarbon fuels, fuel dilution with nitrogen and a range of oxygen/nitrogen ambient environments. Correlation of the data allows one to predict X _R in terms of the: (1) fuel smoke-point laminar flame height, l ₃, (or corresponding heat release rate Q _SP ), (2) adiabatic stoichiometric flame temperature, T _ad of the supplied reactants, and (3) stoichiometric oxidant to fuel mixture mass ratio S. The existence of such a general correlation for S ≥ 12 suggests that the buoyant flame radiation is effectively controlled by only these three reactant properties. The present correlation does not apply for S < 12 because of the increased importance of gaseous radiation for reduced 5. The above correlation of turbulent flame ;X_R with the laminar-flame smoke point is achieved by consistently referring both (turbulent and laminar) flame systems to “Standard Conditions” (S = 15 and T _ad = 2200 K.). Fuel mixture mass concentrations ranged from 0.139 to 1.00; while oxidant oxygen mass concentrations ranged from 0.ISS to 0.302.

Key words:

• Fire
• turbulence
• smoke point
• buoyant
• radiation