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 portraits 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.