中等后掠角三角翼前缘双涡结构的形成机理数值研究

Numerical investigations of formation mechanism about a dual leading-edge vortex structure of a delta wing with medium leading-edge sweep angle

采用数值计算的方法,对前缘后掠角为50°的三角翼布局在不同迎角下的绕流结构及其演化进行了研究。在不同迎角下,计算的压力分布与实验结果吻合较好。对数值计算的流场结构分析发现:对于中等后掠角三角翼,在一定的雷诺数和迎角下,在机翼翼面上会出现前缘双涡结构。其形成取决于三角翼前缘附近三维分离产生的自由剪切层强度和涡轴方向的速度分量之间的大小关系。一般而言,当涡轴的速度大到足以将剪切层涡量带走时,在机翼前缘常常会表现为单涡结构;反之将导致剪切层分叉,由此形成双涡结构。

A numerical investigation of the characteristics and evolution of the structure of the＂ vortical flowfield was carried out on 50°delta wing. The comparison of results shows good agreement between experi- mental studies and the CFD predictions. In this paper, vortical flowfield were analysed and summarized. The results indicate that a dual leading-edge vortex structure is observed under some Reynolds numbers and an- gles of attack for a delta wing of the medium leading-edge sweep angle. The formation of the dual vortex structure of a delta wing is due to the relations among the velocity to the vortex core and the intensity of the separated shear layer that emanates from the leading edge of the delta wing. Generally speaking, a single leading-edge vortex structure is observed on the upper surface of the wing when the velocity to the vortex core is enough to carry off all the separated shear layer, otherwise the shear layer will branch and a dual lead- ing-edge vortex structure will be formed.