EXPERIMENTAL INVESTIGATION OF ENCLOSED ROTOR-STATOR DISK FLOWS

Detailed hydrodynamic measurements were obtained in a rotating water-f low rig for an enclosed rotor-stator system with a stationary outer sh roud. Three different measuring techniques-laser-Doppler anemometry, h ot-film velocimetry, and the yaw-tube method-were employed. Measuremen ts include the variation of the mean and some of the fluctuating veloc ity components across a rotor-stator cavity of aspect ratio 0.127. Sev eral radial locations were examined, and special efforts were made to resolve the near-wall variation. The investigation covers a rotational Reynolds number range, Re-theta, from 0.3 X 10(6) to 1.6 X 10(6). In the detailed picture of the flow structure that emerges, at the higher rotational speeds the Ekman-type boundary layer on the rotor is lamin ar over the inner half of the cavity and turbulent at the outer radial locations. The stator boundary layer, on the other hand, is turbulent over most of the cavity, and the high near-wall turbulence levels ext end further into the core. At lower rotational speeds (Re-theta = 0.3 x 10(6)), the rotor boundary layer is laminar over almost the entire c avity but the stator layer remains turbulent. The differing behavior o n the rotor and stator surfaces is interpreted as a consequence of con vective motion that transports fluid radially outward on the outer sur face but radially inward on the stator. Although the present results b roadly support an earlier study in a narrower cavity covering a smalle r range of Reynolds number, significantly different interpretations ar e drawn in some respects.