Influence of refraction and divergence of light on tomography of axisymmetric laminar diffusion flames

Computerized tomography is a non-intrusive diagnostic technique that can be used to analyze flame structure. This work describes a new algebraic algorithm for tomographic reconstruction of confined laminar axisymmetric flames, considering effects of refraction and divergence of light. A flame cross section is divided in a number of concentric rings of constant refraction indexes with the light rays being refracted at ring interfaces. The algorithm is initially tested with a theoretical flame model placed at different camera distances, with several digital camera resolutions and with different thickness of the confining flame quartz tube. Then, the algorithm is applied to the reconstruction of CH∗ and C 2 ∗ emissions in co-flow diffusion flames, considering refraction throughout the flame and across the burner quartz tube. The influence of refraction and divergence of light on flame tomography reconstruction appears to be significant depending on the parameters values chosen for the theoretical and experimental setup.