UBC Theses and Dissertations
Experimental investigation of the flow field about sharp-edged delta and rectangular wings Sun, Yung-chiun
When a thin delta wing with high leading-edge sweep is placed at incidence in a stream, the fluid separates from the surface at the leading edges and coils up to form a pair of symmetrically placed vortices above the upper surface of the wing. This flow pattern is stable up to high incidence, but at extreme high incidence, the stable vortex core appears to burst or rapidly diffuse. The present research was done as part of a general program to study the vortex bursting phenomenon about sharp-edged delta wings. The aim was to determine the bursting position at different angles of attack and the effect on the wing performance. It was found that the bursting occurs first downstream of the trailing edge and then moves rapidly upstream with increasing incidence. The wing stalls when the bursting point occurs at a position upstream of the wing's trailing edge. The pressure distributions on a sharp-edged rectangular wing were also measured in the present research and the overall normal force coefficient was obtained by the graphical integration of surface pressures. It was found from the pressure distributions that the flow pattern changes from one type to another in the range from ∝= 10° to ∝= 15°. The overall normal force coefficient reaches its first maximum value at 17° incidence.
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