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.
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