Abstract: Detailed investigation of a turbulent separation-reatta-chment flow in a 2-D curved-wall diffuser using TSI model 9100-7, two-color, dual-beam Laser Doppler Velocimeter System. This separation occurs under strong adverse pressure gradient on a convex surface with large curvature, and the separated shear layer reattaches downstream where the adverse pressure gradient becomes milder or under the natural relaxation condition, simulating the actual flows in some engineering applications.Mean velocities U, V and Reynolds stresses u2, v2 and -uv are presented. The preliminary analysis shows that the experimental results are reliable. The entire flow field can be divided into five regions. The reatiaching flow is about twice the length of the separating zone. Due to the separation, the streamwise curvature induces a significant normal pressure gradient near the incipient detachment. It is found that there exists a second peak on u2, as well as a negative of (-uv) having the same order of magnitude as (-uv)max, downstream of the transitory detachment.

Key words: laser anemometer, turbulent flow, separated flow, reattaching flow