Akademik Veri Yönetim Sistemi
JOURNAL OF AIRCRAFT, cilt.42, sa.5, ss.1318-1330, 2005 (SCI-Expanded)
The Reynolds number dependence of the near-surface flow structure and topology on a representative unmanned combat air vehicle planform is characterized using a technique of high-image-density particle image velocimetry, to complement classical dye visualization. Patterns of streamline topology, including bifurcation lines, as well as contours of streamwise and transverse velocity, surface-normal vorticity, and Reynolds stress correlation, all immediately adjacent to the surface of the planform, provide quantitative indicators. At low angle of attack, these indicators show significant alterations with Reynolds number, in accord with large variations of patterns of vortex breakdown and vortex interaction visualized by dye and substantial alterations of flow patterns in the crossflow plane, including reattachment phenomena, which are interpreted with patterns of velocity, streamlines, and streamwise vorticity. On the other hand, at moderate angle of attack, the near-surface quantitative indicators show much less sensitivity to Reynolds number, which is in line with weak variations of the onset of vortex breakdown with changes in Reynolds number.