Song, C. S.Tsai, F. Y.2011-08-302011-08-301966-06https://hdl.handle.net/11299/114197The critical Taylor numbers for five different non-Newtonian solutions were determined experimentally by visual observation using the hydrogen bubble technique. Although three different gap sizes were used, only the data for the smallest size can be considered satisfactorily accurate. Smaller hydrogen bubbles than those used in this experiment are necessary for more aocurate determination. Contrary to a finding by others, the present experiment indicates that the critical Taylor number is decreased as the concentration is increased. The shear on the outer cylinder due to rotation of the inner cylinder was also measured for an intermediate range of Reynolds number, i.e. laminar flow at superoritical Taylor number. Substantial reductions of frictional drag coefficient Were achieved at higher additive concentrations When the comparison was based on equal Reynolds number.en-USReport