轴对称钝物体的尾涡结构

本文对于圆球和70°角斜切尾钝头旋成体的尾涡结构作了流态显示和部分热线测量,流态显示结果表明,这类钝物体尾迹中的三维尾涡结构均呈现为一列相互锁定的“涡链”状结构,每一个涡元素自身并不闭合,呈“发卡”形,并与后继的涡相连接,对于70°斜切尾钝头旋成体模型,由于其斜切尾有固定三维尾涡面卷起和脱落方位的作用,故呈现出规则的三维尾涡结构。而圆球模型,由于涡面卷起和涡脱落的方位是随机旋转的,因此“涡链”呈现为被任意扭曲的千姿百态,流态照片各不相同,圆球尾迹的这种既有周期性又有随机旋转的特性,在热线测量的结果中也有所反映。

VORTEX STRUCTURE IN THE WAKE OF THE AXISYMMETRIC BLUFF BODIES

Vortex structure in the wake of a sphere and a bluff body with a slanted base were investigated by both flow visualization and hot wire measurement. Flow visualization showed that wake configuration consisted of a series interlocking loops. Each vortex element looks like "hairpin vortex", which connect each other in chains. It was found that slanting the base could fix the orientation of the rolling up of vortex sheet as well as the position of vortex shedding, and vortex structure is quite regular. As for the sphere, although each vortex element is similar to hairpin vortex, the vortex loops are not regular due to random rotating of position and orientation of vortex shedding. From hot wire measurement, the difference ia the wake macro-structure between two models is shown to exist statistically, which coincides with the visualization results.