Measurements of Instantaneous Radial Temperature Profiles in Turbulent Diffusion Flames

Abstract

Instantaneous spatial temperature profiles are measured by means of a laser Rayleigh scattering method using a detector which has multiplepoint elements in a single line. The instantaneous temperature profiles could be detected without influence from chemiluminescence by use of a pulse YAG laser. This method was applied to the measurements of three typical turbulent diffusion flames with different degrees of turbulence. The results obtained are as follows. (1) The average and instantaneous maximum temperatures tend to decrease when the Raynolds number increases. (2) The probability density functions (pdf) of temperature in the flame have broad profiles. This indicates that burned gas of various equivalence ratios is mixed in the flame. (3) The rms values of temperature fluctuation both inside and outside of the flame are high. Temperature fluctuations on large spatial scales are predominant in the flames. The scales of the temperature fluctuations do not depend significantly on the Raynolds number.