非定常集中涡破裂形态及其对扰动的影响

THE FORMS OF UNSTEADY CONCENTRATED VORTEX-BREAKDOWN AND ITS REACTIONS TO DISTURBANCE

本文中利用三角翼前缘涡襟翼的强制振动来推迟涡破裂。流场显示实验结果表明,在有强制扰动时,集中涡显示出两种不同形式的破裂,可分成六种不同的破裂形态。非定常集中涡的一个破裂过程涉及几种破裂形态之间的转换。涡襟翼振动产生的非定常效应对涡破裂的影响与三角翼后掠角有密切的关系,随后掠角增大非定常效应的影响变小。就实验迎角范围而言(α<35°),对50°后掠角三角翼,涡襟翼振动可显著推迟涡破裂;但对70°后掠角三角翼,振动却能促进涡的破裂。涡襟翼振动改变了集中涡的性态,使集中涡趋向于和前缘平行。振动对涡破裂的作用部分地与这种效应有关。

The forced oscillation of leading-edge vortex-flap on delta-wing is used to suppress vortex breakdown. The flow visualizations of water channel experiments reveal that,under forced disturbances, there are two types of concentrated vortex-breakdowns,which in turn can be divided further into six patterns. The unsteady concentrated vortex-breakdown may involve a process of switching among several breakdown patterns. The effects of vortex-flap oscillations upon vortex-breakdown are closely related to the sweep angles of the delta wing, which would be weakening as the sweep angles increasing. In the norm of angles of attack in the experiments (a<35°) ,the oscillations of the vortex-flap can largely delay the vortex-breakdown for delta wing with sweep angle of 50°;for sweep angle of 70°,however,it is found that the oscillations would become detrimental to the vortex-breakdown. The state of concentrated vortex is changed with the vortex-flap oscillation,and vortex tends to be parallel to the leading-edge. The action of the oscillation toward vortex-breakdown in due partly to the effect.