Effects of coarse riblets on air flow structures over a slender delta wing using particle image velocimetry

This research investigates the aerodynamic performance and flow characteristics of a delta wing with 65° sweep angle and with coarse axial riblets, and then compares with that of a smooth-surface delta wing. Particle Image Velocimetry (PIV) were utilized to visualize the flow over the wing at 6 cross-sections upright to the wing surface and parallel to the wing span, as well as 3 longitudinal sections on the leading edge, symmetry plane, and a plane between them at Angles of Attack (AOA) = 20° and 30° and Re = 1.2 × 10 5 , 2.4 × 10 5 , and 3.6 × 10 5 . The effects of the riblets were studied on the vortices diameter, vortex breakdown location, vortices distance from the wing surface, flow lines pattern nearby the wing, circulation distribution, and separation. The results show that the textured model has a positive effect on some of the parameters related to drag reduction and lift increase. The riblets increase the flow momentum near the wing’s upper surface except near the apex. They also increase the flow momentum behind the wing.