Simultaneous water vapor concentration and temperature measurements in unsteady hydrogen flames

Techniques applicable to visualization and scalar Measurements in large-scale hydrogen fires are highly desired, but lacking. In this research, planar thermal images of a buoyancy-driven unsteady laminar hydrogen/air flame and line images of a thin filament stretched across this flame were obtained using ail infrared (IR) camera at a sampling frequency of 348 Hz. A Pulsing frequency of 11 Hz was measured. Transient line measurements of temperature (T) and water vapor mole fraction (X-H2O) have been achieved using, inverse radiation calculations. Instantaneous X-H2O and T distributions during a flame-vortex interaction cycle were obtained with temporal and spatial resolutions of 3 ms and 1.7 mm, respectively. The instantaneous distributions of X-H2O and T were effected by preferential diffusion and the altered velocity field of the flame. Vortices caused more scalar fluctuations outside the flame surface than inside. The present X-H2O and T measurements are consistent with detailed chemistry calculations of the flame and laser diagnostic measurements of similar flames. With some modifications, the thermal imaging based technique can be extended to large-scale hydrogen fire applications. (c) 2009 The Combustion Institute. Published by Elsevier Inc. All rights reserved.