Investigation of crossflow features of a slender delta wing

摘要

In the present work, the main features of primary vortices and the vorticity concentrations downstream of vortex bursting in crossflow plane of a delta wing with a sweep angle of Lambda=70 degrees were investigated under the variation of the sideslip angles, beta. For the pre-review of flow structures, dye visualization was conducted. In connection with a qualitative observation, a quantitative flow analysis was performed by employing Particle Image Velocimetry (PIV). The sideslip angles, beta were varied with four different angles, such as 0 degrees, 4 degrees, 12 degrees, and 20 degrees while angles of attack, alpha were altered between 25 degrees and 35 degrees. This study mainly focused on the instantaneous flow features sequentially located at different crossflow planes such as x/C=0.6, 0.8 and 1.0. As a summary, time-averaged and instantaneous non-uniformity of turbulent flow structures are altered considerably resulting in non-homogeneous delta wing surface loading as a function of the sideslip angle. The vortex bursting location on the windward side of the delta wing advances towards the leading-edge point of the delta wing. The trajectory of the primary vortex on the leeward side slides towards sideways along the span of the delta wing. Besides, the uniformity of the lift coefficient, C-L over the delta wing plane was severely affected due to unbalanced distribution of buffet loading over the same plane caused by the variation of the sideslip angle, beta. Consequently, dissimilarities of the leading-edge vortices result in deterioration of the mean value of the lift coefficient, C-L.