VORTEX GENERATION AND PROPERTIES OF TRANS ITION TO TURBULENCE IN A TAYLOR-COUETTE FLOW SYSTEM WITH SMALL ASPECT RATIO

The generation of vortices and transitional properties to turbulent fl ow in a Taylor-Couette flow system with an aspect ratio of 3 were inve stigated in terms of the effect of the acceleration of the inner cylin der rotation speed by using numerical, electrochemical and flow-visual ization techniques. The three-dimen-sional simulation based on the SMA C method clarified the generation mechanism of vortices and temporal a nd spatial properties in a wavy vortex flow. The electrochemical and f low-visualization techniques revealed the temporal and spatial propert ies in wavy, quasi-periodic wavy and weakly turbulent wavy vortex flow s. Lower acceleration rates produced the two-cell primary mode, while the four-cell secondary mode was generated in the case of higher accel eration rates. In a wavy vortex flow, the single fundamental frequenci es, which correspond to the passing frequencies of the travelling azim uthal waves, velocity and velocity gradient power spectra depend on th e flow modes. In quasi-periodic and weakly turbulent wavy vortex flows , the temporal-spatial properties also largely depend on the cell mode s. These results suggest that the geometric structure of vortex cells influences flow characteristics.