The effect of angle of attack on the flow structure over the nonslender lambda wing

The aim of the current study at first stage is to demonstrate the general flow structure qualitatively using the dye visualization technique. Secondly, the instantaneous flow data taken by a Stereoscopic Particle Image Velocimetry (stereo-PIV) over a stationary nonslender lambda wing is used to determine the time-averaged flow topology in order to provide detailed information about crucial events like formation of leading edge vortices and vortex breakdown in plan-view planes and cross-flow planes. The flow structure close to the lambda wing surface and development of the vortex breakdown are investigated as functions of angles of attack within the range of 7 degrees <= alpha <= 17 degrees. Experimental analyses are composed of time-averaged patterns of streamlines, vorticity contours, transverse and streamwise velocity components, Reynolds-stress correlations, distribution of fluctuating velocities, and turbulent kinetic energy. Results show that the angle of attack has a substantial influence on the flow behavior on the nonslender lambda wing surface. (C) 2013 Elsevier Masson SAS. All rights reserved.