Stagnation Point Heat Transfer from Turbulent Methane-Air Flames

Abstract

Mathematical models for the prediction of stagnation point heat flux in the chemical equilibrium region of turbulent flames are presented. These models include a numerical solution of the relevant boundary layer equations, and modified empirical correlations originally derived for the case of uniform, turbulent air flows. Experimental measurements of the stagnation point heat flux received by a hemisphere-cylinder probe placed in methane-air flames are included, and free stream temperatures, mean velocities and turbulence intensities were measured for comparisons between theory and experiment. Predictions of the mathematical models show that the influence of free stream turbulence on heat transfer from these names is relatively small for the geometry in question. Comparisons with experimental data confirm this finding. Good quantitative agreement occurs between numerical solutions and experimental data for flames which only entrain small amounts of atmospheric air. Conservative estimates of heat transfer rates are obtained from the modified empirical correlations proposed.