FLOW BETWEEN CONTRAROTATING DISKS

The paper describes a combined experimental and computational study of laminar and turbulent flow between contrarotating disks. Laminar comp utations produce Batchelor-type flaw: Radial outflow occurs in boundar y layers on the disks and inflow is confined to a thin shear layer in the midplane; between the boundary layers and the shear layer, two con trarotating cores of fluid are formed Turbulent computations (using a low-Reynolds-number k-epsilon turbulence model) and LDA measurements p rovide no evidence for Batchelor-type flow, even for rotational Reynol ds numbers as low as 2.2 x 10(4). While separate boundary layers are f ormed on the disks, radial inflow occurs in a single interior core tha t extends between the two boundary layers; in the core, rotational eff ects are weak. Although the flow in the core was always found to be tu rbulent, the flow in the boundary layers could remain laminar for rota tional Reynolds numbers up to 1.2 x 10(5). For the case of a superpose d outflow there is a source region in which the radial component of ve locity is everywhere positive; radially outward of this region the flo w is similar to that described above. Although the turbulence model ex hibited premature transition from laminar to turbulent flow in the bou ndary layers, agreement between the computed and measured radial and t angential components of velocity was mainly good over a wide range of nondimensional flow rates and rotational Reynolds numbers.