Temperature measurements in a wall stabilized steady flame using CARS

Abstract

Flame quenching by heat loss to a surface continues to be an active area of combustion research. Close wall temperature measurements in an isothermal wall-stabilized flame are reported in this work. Conventional N2-vibrational Coherent Anti-Stokes Raman Scattering (CARS) thermometry as close as 275 µm to a convex wall cooled with water has been carried out. The standard deviation of mean temperatures is observed to be ~6.5% for high temperatures (>2000K) and ~14% in the lower range (<500K). Methane/air and ethylene/air stoichiometric flames for various global strain rates based on exit bulk velocities are plotted and compared. CH* chemiluminescence is employed to determine the flame location relative to the wall. Flame locations are shown to move closer to the wall with increasing strain rates in addition to higher near-wall temperatures. Peak temperatures for ethylene are considerably higher (~250-300K) than peak temperatures for methane. Preheat zone profiles are similar for different strain rates across fuels. This work demonstrates close wall precise temperature measurments using CARS.