Turbulence measurements in drag reducing flow

"Studies of the frequency response of hot-film wedge probes in viscoelastic fluids established their reliability as measuring devices and demonstrated that the objections raised by Metzner and Astarita (77) are not valid for wedge probes. The structure of turbulence in drag reducing soap and polymer solutions was studied using a hot-film wedge probe. Intensity of turbulence measurements in drag reducing fluids indicate that the structure of trubulence is strongly dependent on the condition of the solution. Rates of energy dissipation calculated at the center of the tube indicate that there is an increase in the rate of energy dissipated in the central core of the tube. This indicates that the basic mechanism for drag reduction appears to be the storage and diffusion of energy from the wall to the central core of the tube, as proposed by Walsh (122). Rates of energy dissipation at the center of the tube were correlated using the Deborah number as an indication of the degree of degradation of the solution. Comparisons of several commonly-used hot film probes in purely viscous fluids indicate that deviations of 20% for measured turbulence intensities can be obtained, due to effects of probe geometry; normalized energy spectra measured with the same probes were similar, even though the measured turbulence intensities were different. Comparisons of intensities of turbulence in drag reducing fluids measured with a total pressure probe and a bot-film wedge probe indicates that there are differences between the results obtained with these two types of probes, which can be attributed to viscoelastic effects on the pressure probe measurements"--Abstract, pages ii-iv.

Name thesis:degree_name

Ph. D. in Chemical Engineering

Grantor

University of Missouri--Rolla

Year dc:date.available

2016

Author dc:creator

• Rodriguez, Jorge Mario

• Chemical Engineering

Repository record dc:identifier

https://scholarsmine.mst.edu/doctoral_dissertations/2318

OAI identifier oai:identifier

oai:scholarsmine.mst.edu:doctoral_dissertations-3320