Effects of yaw angle on vortex formation downstream of a slender delta wing

In the present work, basic features of counter rotating pair of leading edge vortices and vorticity concentrations downstream of vortex breakdowns in end-view planes of the delta wing with 70° sweep angle, Λ were experimentally studied both qualitatively and quantitatively using Rhodamine dye and the particle image velocimetry (PIV) technique. Experiments were conducted by altering angles of attack within the range of 25°≤α≤35° and yaw angles, β within the range of 0°≤β≤20°. Present investigation focused on crossflow structures in sequentially- located at five different end-view planes along the cord axis, C at locations x/C=0.2, 0.4, 0.6, 0.8 and 1.0. A trajectory of leading edge vortices, locations of vortex breakdown, and vorticity concentrations occurring downstream of vortex breakdowns and their interactions were observed using dye visualizations. Time-averaged velocity vectors , pattern of streamlines,<ψ> velocity components, u and v, contour of vorticity distributions, <ω> and root mean square of streamwise velocity, /U and transverse velocity, /U components were determined by the PIV technique. When the delta wing is yawed, macro scale symmetrical flow structures are altered considerably. The windward side vortex breakdown location moves towards the apex of delta wing. Trajectories of leading edge vortices slide sideway close to the central axis of the delta wing.