涡与涡以及涡与附面层之间相互作用的试验研究

AN EXPERIMENTAL INVESTIGATION ON INTERACTIONS AMONG VORTICES AND VORTEX WITH BOUNDERY LAYER

涡由叠合式三角形涡流发生器产生。对涡与涡之间的相互作用研究表明，反向旋转涡之间相互作用使得相邻涡之间向上或向下速度增加。同向旋转涡之间相互作用造成相邻涡的干扰，使涡变弱。对涡与附面层之间的相互作用研究表明，涡改变了附面层的速度分布，使附面层内层速度分布饱满，减小了附面层形状因子。附面层对涡的作用使得涡的耗散大大加快，涡量减小，涡核半径变大，涡的有效作用距离减小。

An experimental investigation on the interactions among vortices and the vortex with boundery layer was performed with a boundery pressure probe and a small-size five-hole pressure probe,which can both be placed at any point in the flow field by an accurate small-displacement coordinate apparatus.The vortices were generated by doubled half delta ramp submerged Vortex Generators (VG).The counter-rotating vortices interaction increased the down-washed and up-washed velocity,and the distance of the interaction may reach 50 h (the height of the VGs) or more.The interaction between two ajacent co-rotating vortices was counteractive,and due to their mirror-image interaction the crossflow underneath the vortex core was larger than that above it,so that stronger second flow near the wall was generated.The strength of co-vortices decreased so rapidly downstream that the vortices began to break out and disappear at distance from 20th to 30th,however the second flow velocities near the wall were still large even at distance from 30th to 40th.The effect of the vortices on the boundary layer improved the velocity distribution in boundary layer i.e.,the velocity profile near the wall became fuller both in up-washed and downd-washed field,so the shape factors in both fields became small.The boundary layer leads to intense exhaustion of the vortex due to its strong interference.As a result,the strength of the vortex in thick boundery layer became smaller than that in thin boundery layer,and the radius of vortex core became larger,and the effective distance of the vertex lessened.