Electrochemical Study of Taylor-Couette Flow by Limiting Diffusion Current Method

Abstract

Steady Taylor vortices were studied by electrodiffusion probes in the gap between coaxial cylinders. The inner cylinder was driven by a stepping motor and the outer cylinder was fixed. The viscosity of standard potassium hexacyanoferrates (III) and (IV) aqueous solution was increased to 2.52 mPa s by addition of poly(alkylene glycol) Emkarox 45. The velocity gradient components were measured by two three-segment probes at the wall of the outer cylinder for four radius ratios, R1/R2 = 0.8, 0.75, 0.65 and 0.6. The axial distribution of the azimuthal and axial components of velocity gradient was mapped while Taylor vortices were swept along the probes by a slow axial flow. The components of velocity gradient were described by fourth-order Fourier series. Generalized dependencies were found of the Fourier coefficients on Taylor number. A vertical shift of the probes made it possible to calculate the wavelength and the drifting velocity of Taylor vortices. Critical Taylor numbers were estimated from the axial component of velocity gradient and by the flow visualization using a rheoscopic liquid. The torque was calculated from the azimuthal component of velocity gradient.