Aerodynamics of a Burning Turbulent Gas Jet in a Crossflow

Abstract

A theoretical treatment is presented of the motion of a turbulent gas jet burning in an oxidizing crossflow. The study represents a significant extension of the entrainment theory for weak plumes, through the incorporation into its framework of the influences of radiative thermal-energy transfer, large density variations, and thermal-energy generation through chemical reaction. Numerical calculations are presented for the variation of bulk temperature and species concentrations along the plume trajectory. The concentrations are shown to be strongly coupled with the temperature, suggesting a possible simplification of the problem of calculating the production rates of pollutants formed in secondary reactions. Thermal radiation is found to be of secondary importance to plume dynamics. Comparisons are made between exact (numerical) and approximate (asymptotic) calculations of plume trajectory, with and without thermal energy release. These calculations show that for conditions typical of those encountered in a gas-fired furnace, a plume's motion is not significantly influenced by buoyancy forces until well downstream of the reaction zone.