COLLABORATION IN BASIC SCIENCE AND ENGINEERING (COBASE)

The collaborative research between Ralph Pike and his Bulgarian colleague, Serafim Vlaev, focused on the measurement and analysis of gas dispersions in multi-phase chemical reactors using optical tomography. The main objectives of this study were threefold: (1) to apply optical tomography to measure gas dispersion distributions in gas-liquid flow in a stirred chemical reactor with the standard tank configuration; (2) to generate 3-D mapping of local gas hold-up in order to analyze gas-liquid circulation flow and to estimate gas hold-up non-uniformity in cases of practical importance; and (3) to select specific issues for further analysis and long-term collaboration.

The two scientists conducted their two-week study in early March 2000 at the Department of Chemical Engineering at Louisiana State University and were quite successful in meeting the stated objectives. Out of the six gas-liquid systems that were tested, two (i.e. water and 1% CMC) were found appropriate for optical measurements and were subjected to further testing in a total of 20 different mixing conditions. Calibration runs "gas hold-up versus gray light intensity" were carried out for the two liquids using metering flasks. In total, 23 pairs of frames were identified and transferred into separate files for image reconstructing processing.

Unfortunately, there was not enough time in the two-week period to obtain the measurements and complete the image processing and optical tomography evaluations necessary to reconstruct a 3-D void fraction pattern. A new C+ program has been added for transition from raw file format to FORTRAN readable file containing the specific numerical values. Currently, the two scientists are working on an NSF proposal, which would enable them to continue their study of optical tomography and image processing methodology.