Preprint version of "Laser Doppler Anemometry Measurements in an Index of Refraction Matched Column in the Presence of Dispersed Beads" by S. Haam, R.S. Brodkey, I. Fort, L. Klaboch, M. Placnik and V. Vanecek.

Laser Doppler anemometry (LDA) was used to measure the velocity in a liquid flow field in the presence of dispersed be ads.Axial and radial velocity components were measured, mainly at the center of the column. Index of refraction matching between the fluid and solid beads was essential to extract the turbulence data from the fluid phase because of the high concentration of beads. An excellent index of refraction match was obtained between the fluid (para-cymene) and the dispersed solids (PMMA beads). This allowed adequate measurements of the turbulent fluid velocities without generating noise from the surface of the beads.

The LDA experimental data base for the turbulent dispersed flow was obtained under transient flow conditions. This approach avoided the need for a complex solids circulation system. The resulting data were statistical and ensembled averaged for short periods during the transient experiments where the concentration could be taken as approximately constant. The concentration levels were determined from separate particle tracking velocimetry measurements (PTV), to be described in Part II. Many independent transient runs were made to insure that a statistical significant sample was obtained.

The bead density was greater than the fluid and thus wakes were created. These local areas of fluid experienced a lowering of the velocity. The turbulent fluctuation results showed that the presence of the beads extracted energy from the mean flow and transferred that energy to the turbulence. The increase of turbulent intensity was impressive along the centerline of the column where the measurements were made. The axial turbulent intensity of the fluid without beads was of the order of 10% and with beads, the level was increased to nearly 70%.