Flow structure over the yawed nonslender diamond wing

The aim of this study is to qualitatively and quantitatively investigate the flow characteristics of a nonslender diamond wing with a sweep angle of Λ = 40 ° by using dye visualization and a stereoscopic Particle Image Velocimetry (stereo-PIV) technique. The flow structure near the stationary diamond wing surface and the formation of the vortex breakdown were studied by varying the yaw angle within the range of 0 ° ⩽ θ ⩽ 15 ° and varying the angle of attack within the range of 10 ° ⩽ α ⩽ 17 ° . Experimental analysis is composed of the time-averaged patterns of streamlines, contours of vorticity distributions, Reynolds stress correlations, transverse and streamwise velocity components, distribution of fluctuating velocities, and turbulent kinetic energy for interpreting the flow physics. It is found that the formation of the vortex breakdown and vortical flow structures are sensitive to the yaw angle; the distributions of the time-averaged flow data over the surface of the diamond wing alter profoundly when the yaw angle of the diamond wing is increased by over 6°. The magnitude of the turbulent kinetic energy decreases on the leeward side of the wing surface because the formation of the vortex breakdown occurs farther downstream than on the windward side, causing less concentrated velocity fluctuations over the wing surface on the leeward side.