Abstract
Boundary-layer transition on a concave curved plate has been investigated with and without periodic-unsteady inlet flow at zero and negative pressure gradients. The periodicunsteady wakes were created using a rotating squirrel-cage type wake generator. The transition procedure without wakes present appeared to be classical Tollmien-Schhchting wave formations that were possibly modified by longitudinal Gbrtier vortices. The presence of a negative pressure gradient delayed the onset of transition over that of a zero pressure gradient. A complete ensemble-averaged visualization of periodic-unsteady transition is also presented. The wake strip initiated a disturbance into the boundary-layer at the leading edge of the plate. Afterwards, the wake strip in the free-stream and the disturbance in the boundary-layer appeared to independently convect downstream. Larninar regions were observed between wakes far beyond the streamwise position they are confined to in the corresponding case without periodic-unsteady wakes. In addition, a turbomachinery cascade test facility with periodic-unsteady inlet flow was designed and manufactured for the next generation of research in this area.
Radke, Robert Edward (1994). The effect of periodic-unsteady wakes, curvature, and pressure gradient on boundary-layer transition. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1994 -THESIS -R1293.