Quantitative molecular-mixing measurements using digital processing of absorption images

Absorption imaging was used to measure the chemical product formed in a nonpremixed reacting turbulent water-jet. A collimated light-beam was absorbed by red phenolphthalein formed through a chemical reaction between neutral (pH 7) jet fluid and alkaline tank fluid. The integrated absorption was imaged on a CCD camera. Standard single-point absorption technique was thus extended to allow simultaneous measurement of absorption over a two-dimensional field. Digital image processing techniques were applied to obtain the time-average of the integrated chemical product. Product-concentration profiles in the natural jet were obtained using Abel inversion. The chemical product present six diameters downstream of the jet exit was increased 35 percent by the addition of two tabs.

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