Abstract:

The hydrogen bubble technique was used to visualize the development and variation of a backward facing step laminar separation flow, which covered basic flow and its unsteady control. The unsteady disturbance was introduced by a wake vortex generated by a fine wire located upstream the step. The visualization results indicate that the fine wire delays the shear layer reattachment in most cases, and that only when the fine wire is at the positions x w /h=0 and y w /h=0.5, the shear layer reattachment distance could be decreased.

Key words: backw ard facing step, laminar boundary layer separation, flow unsteady control, flow visualization