Assessment of a partial-equilibrium/monte carlo model for turbulent syngas flames

Abstract

Calculations and data for a turbulent jet flame of 40% CO, 30% H 2, and 30% N 2 in coflowing air are compared extensively. The calculations are based on a partial-equilibrium model for the oxyhydrogen radical pool including CO, and on a velocity-composition joint probability density function (pdf), which closes the turbulent flux and mean chemical source terms. The pdf is joint between the three velocity components and two thermochemical scalars needed to describe partial-equilibrium conditions. The equation is solved numerically by a Monte Carlo technique. The data used are major species concentrations and temperature from pulsed Raman scattering. Difficulties with Raman measurements at high temperatures and of measuring CO 2 directly are discussed. The Raman signals are taken from previous studies but here are corrected for high-temperature effects and CO 2 vibrational spectra. Temperatures are obtained from the instantaneous density of the major species rather than from the Stokes/anti-Stokes ratio, which is more affected by chemiluminescence. The level of agreement between the model and the data is more favorable to the partial-equilibrium model than previously thought. The relative simplicity of the partial-equilibrium model makes it a candidate for practical calculations.