Colour ratio pyrometry is an economic and rapid technique to obtain soot temperatures and volume fractions from colour photographs of flames. One of the key challenges is to reconstruct the light intensity at the flame cross section R(r,z) from its 2D projection recorded by the camera P(x,z), also known as the inverse Abel transform (see illustration). In a recent project, our group developed a new Abel inversion method (FLiPPID) tailored to the analysis of co-flow diffusion flame images. Advantages over conventional methods are a less noisy image reconstruction and the suppression of nonphysical negative light intensities.
The Python code for performing the image analysis is available here (see also our software page). An example image and data are also available (FlPyroImageAndData.zip, 20 MB). The code can be used to compute 2D soot temperature and volume fraction profiles from colour photographs using different methods for the inverse Abel transform (FLiPPID, BASEX, or onion-peeling combined with a Tikhonov regularisation). A more detailed description can be found in Preprint 217 as well as the comments within the Python code. The sequence of steps performed by the provided code are shown in the flow-chart below.