飞行器头部的涡系结构研究

通过三阶精度离散格式求解N-S方程,模拟了飞行器头部涡系流动过程,展示了不同层次的涡系结构.结果表明,较小攻角时,表面不同的鞍点与结点拓扑组合,在飞行器头部空间演化出不同的涡系.稳定螺旋点在空间演化为羊角涡,促使对称主涡向非对称发展.较大攻角时,头部空间演化出U型马蹄涡,通过牵制主涡涡核,抑制主涡向非对称发展.中等攻角时,飞行器头部既形成羊角涡,又形成马蹄涡,二者对主涡的作用是相反的.

Vortex Flow Structure over the Nose of Aircraft

Using time-dependent compressible Navier-Stokes equations with finite volume incorporating a third-order-accurate discretization scheme, flow structure over the nose of aircraft is simulated, and different types of vortex series are described clearly. The result shows that, at lower angles of attack, the topological combination type of saddle and node on the surface of the nose develops to different spatial vortex series at the nose of the aircraft. Horn vortices are developed from the stabilized spiral point. They are severe disturbances driving the main vortices developing to the asymmetric state. At certain higher angles of attack, a U-shaped horseshoe vortex at the nose that checks the development of asymmetry containing the vortices cores of the main ones. At middle angles, both the horn vortex and horseshoe vortex are developed at the nose, the two types of the vortices have opposite effect on the asymmetry of the main vortices.