Turbulent and Mean Flow Measurements in an Incompressible Axisymmetric Boundary Layer with Incipient Separation

Measurements have been performed of mean and fluctuating velocities as well as of Reynolds and wall shear stress in an incompressible axisymmetric turbulent boundary layer with a severe adverse pressure gradient. In the flow region where separation was incipient and, further downstream, where reverse flow occurred, only the x-components u and u′ and the skin friction were measured. The measurements were carried out by using conventional hot wires, pulsed wires and surface fences. A comparison of hot-wire and pulsed-wire measurements showed good agreement also at high local turbulence levels as long as the flow did not reverse; large discrepancies were found, however, close to those positions in the flow where the flow velocity changed sign and in the separated region of the boundary layer.