Image processing and correction of the apparent broadening of species concentration profiles in laminar counterflow flames

Abstract

This work study the influence of the light refraction in the apparent broadening of species experimental profiles in counterflow premixed flames. In fact, in a counterflow premixed flame, is generated a layered medium by the temperature gradient which induces a change in the milieu refractive index, causing a deviation of rays emitted by each point of the flame, and therefore producing a broadening of species experimental profiles. The Gladstone-Dale relation was used to estimate the medium refractive index along the burner axis, taking into account the gas density and composition. And then Snell's law for an inhomogeneous medium was used in order to estimate the light refraction, due to the variation of the medium refractive index. As it will be shown, for counterflow premixed flames, the light refraction is negligible, due to the low variation of the medium refractive index along the counterflow burner. However, the same procedure described here can be used to study the light refraction in other experimental configurations, where the medium refractive index varies considerably.