Formation of Taylor Vortex Flow of Polymer Solutions

Abstract

Laser-induced fluorescence (LIF) was applied for the flow visualization of the formation of a Taylor vortex, which occurred in the gap between two coaxial cylinders. The test fluids were tap water and glycerin 60 %wt solution as Newtonian fluids; polyacrilamide (SeparanAP-30) solutions in the concentration range of 10 to 1000ppm and polyethylene-oxide (PEO15) solutions in the range of 20 to 1000ppm were tested as non-Newtonian fluids. The Reynolds number range in the experiment was 80<Re<4.0×103. The rotating inner cylinder was accelerated under the slow condition (dRe*∕dt⩽1min−1) in order to obtain a Taylor vortex flow in stable primary mode. Flow visualization results showed that the Görtler vortices of half the number of the Taylor cells occurred in the gap when the Taylor vortex flow was formed in the primary mode. In addition, the critical Reynolds number of the polymer solutions increased, where Taylor vortices occur, because the generation of the Görtler vortices was retarded. In high concentration polymer solutions, this effect became remarkable. Measurements of steady-state Taylor cells showed that the upper and lower cells of polymer solutions became larger in wavelength than those of the Newtonian fluids. The Taylor vortex flow of non-Newtonian fluids was analyzed and the result obtained using the Giesekus model agreed with the experimental result.