Affiliations: Graduate School of Engineering, Tokyo Metropolitan
University, Hachiooji-shi, Tokyo, 192-0397, Japan. E-mail:
keizo@ecomp.metro-u.ac.jp | Engineering Research Center, Toshiba Carrier Co. Ltd.,
Fuji-shi, Shizuoka, 410-0395, Japan | Graduate School of Engineering, Tokyo Metropolitan
University, Hachiooji-shi, Tokyo, 192-0397, Japan
Abstract: The hydrodynamic instability of surfactant solutions between two
coaxial cylinders was investigated by using a laser-induced-fluorescence flow
visualization technique to clarify the effect of drag-reducing additives on
vortex formation in Taylor-Couette flow. The test fluids were Ethoquad O/12
surfactant solutions, which have a gel-like structure called
"shear-induced structure" (SIS). Photographs of the
formation of Görtler vortices were taken and compared with these of tap water.
In the Taylor number range of 1.2 × 10^5 ⩽ T_a
⩽ 7.1×10^5, tap water and 10 ppm surfactant solution
flows consisted of Taylor vortices and much smaller Görtler vortices at the
rotating inner wall. However, for 50 and 100 ppm surfactant solutions, Taylor
vortices were not apparent and Görtler vortices were collapsed. Measurements of
the wavelength of Görtler vortices lead to the conclusion that surfactant
solutions have a stabilizing effect on Görtler instabilities. This effect
depends on surfactant concentration and becomes considerable with increasing
acceleration of the inner cylinder.
Keywords: Visualization, Non-Newtonian Flow, Surfactant solutions, Taylor cell, Görtler vortices
