Phase Portraits and Flow Regimes in a Circular Couette System with Counter-Rotating Cylinders

Experiments have been conducted on the circular Couette system, established recently in our laboratory. By using an optical-electronic modulation feedback Laser Doppler Velocimetry technique, the velocity time series data with higher signal-noise ratio, power spectra, phase ort traits and Poincare sections were obtained. Two scenarios to chaos were observed. One is the Ruelle-Takens scenario, while the other (when both cylinders of the Couette system are counter-rotating) is quite different from it. A tremendous variety of flow regimes and a new state were observed. A tentative explanation is made for the new state.