Numerical simulations of soot-radiation from buoyant turbulent wall-bounded diffusion flames

Abstract

Buoyant, turbulent diffusion flames anchored on a slot burner in the presence of an isothermal, low-temperature (333 K) wall have been numerically simulated. A laminar smoke point based subgrid (flamelet) radiation model has been applied toward estimation of overall radiant fractions and radiant power distributions of the ethylene fires. The model uses a turbulent micro-scale strain rate and an enthalpy defect that influence the flamelet soot radiation. In the presence of the isothermal, low-temperature wall, the radiant fractions of the fires are observed to decrease along with a reduction of their peak radiant power output. Predicted flame heights, radiant fractions and radiant power distributions are found to reproduce observed experimental trends and exhibit quantitative agreement with measurements. Comparison of radiant power distributions are also made for fires adjacent to high-temperature (1000 K) isothermal and adiabatic walls and peak radiant power output for both scenarios are found to be higher compared to the isothermal, low-temperature wall-bounded fire.