ИСТИНА

Abstract Flows between concentric, counter rotating spherical boundaries are under investigation in a gap with a size equal to the inner sphere radius. The outer sphere rotational rate is fixed, while the inner sphere rotational rate was modulated. The amplitudes and frequencies of modulation are small relative to the averaged rotational rates of both spheres. With modulation amplitude increase, a transition from initial periodical flow to chaos occurs. To determine the state of the flow, time series of azimuthal velocity were used. Measurements were carried out by laser Doppler anemometer. Flow states with chaos–chaos and cycle–chaos–chaos intermittency were detected. The quantitative characteristics are considered, which allow separate different patterns of the flow state with distinct properties.