Dynamics of tip vortices on plunging wings
Dynamics of tip vortices on plunging wings
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DOI：
10.1016/j.ast.2022.107761
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发表时间：
2022-07
影响因子：
5.6
通讯作者：
O. Son;Zhijin Wang;I. Gursul
中科院分区：
文献类型：
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作者：
O. Son;Zhijin Wang;I. Gursul
通过水洞三维测速研究了振荡翼尖涡在周期性和瞬态俯冲运动中的涡动力学特性。最大俯冲速度与自由流速度之比V pmax/U∞在0.1 ~ 1.5范围内变化。在较低的突降速度和频率下，叶顶涡表现为准稳定的直涡丝。随着机翼运动频率和幅度的增加，涡丝上的三维变形以螺旋波的形式出现，同时与尾缘涡合并。在循环过程中，当叶顶涡环流接近最大时，出现不稳定波。在周期性和瞬态俯冲运动中，经涡旋核半径归一化的波长在λ/a= 2 ~ 4范围内变化。我们发现与孤立涡旋的理论预测有相当的一致性。很可能是由于翼流和其他涡旋的存在导致了刺激叶顶涡核心的应变和扰动。我们认为叶尖涡的不稳定性产生机制与前缘和尾缘涡的不稳定性产生机制相似。
The vortex dynamics of the tip vortices on oscillating wings in periodic and transient plunging motions are investigated via three-dimensional velocimetry measurements in a water tunnel. The ratio of the maximum plunging velocity to the freestream velocity V pmax/U∞ is varied in the range of 0.1 to 1.5. At lower plunging velocity and frequency, the tip vortex appears quasi steady as a straight vortex filament. With increasing frequency and amplitude of the wing motion, three-dimensional deformations appear as helical waves on the vortex filament while merging with the trailing-edge vortices also takes place. The instability waves appear as the circulation of the tip vortex approaches near its maximum during the cycle. The wavelength normalized by the vortex core radius varies in the range of λ/a= 2 to 4 for the periodic as well as transient plunging motion. We found reasonable agreement with the theoretical predictions for isolated vortices. It is likely that the presence of the wing flow as well as other vortices result in the strain and disturbances that excite the tip vortex core. We propose that the mechanism of generation of instabilities on tip vortices is similar to those of the leading-edge and trailing-edge vortices.