抄録
Bifurcation phenomena in a finite-length Taylor-Couette flow system have been observed by an electrochemical technique. The axial wavelength was varied as the characteristic parameter of vortex cell structure by varying the aspect ratio of the annular flow space and controlling the inner cylinder acceleration up to a steady rotation speed. Multi-resolution analysis in wavelets was used not only for noise reduction, but also for extraction of low frequency components from the experimental time-series data. When the dimensionless axial wavelength λ/d < 1, the first fundamental frequency f1/fr of singly periodic wavy vortex flow was fixed at a unique value independent of the magnitude of λ/d. When λ/d ≥ 1, on the other hand, f1 was not fixed uniquely but showed some variation, depending on the magnitude of λ/d. In the transition to doubly periodic wavy vortex flow, not only Hopf bifurcation but also two-cycle period doubling bifurcation occurred in some cases when λ/d < 1. The first and second fundamental frequencies, f1 and f2 have tendencies to increase with increasing λ/d in spite of some exceptions. In the process of a transition to weakly turbulent wavy vortex flow, two-torus motion in phase space broke up at all wavelengths without frequency locking.
