Evolution and Interaction of Yawed Surface Jets within a Turbulent Boundary Layer ssion

Interactions of arrays of adjacent yawed rectangular wall jets with the inner layer of a flat plate turbulent boundary layer are investigated in wind tunnel experiments. It is shown that each yawed jet forms a surface bound single sign vortex, remains close to the surface, and enhances the streamwise momentum flux, entrainment and mixing near the surface. The effects of the jets’ absolute and relative yaw angles and strengths on their interactions within the boundary layer are investigated using a pair of adjacent jets with specific emphasis on their streamwise evolution and enhancement of momentum flux in the wall layer. It is shown that the streamwise evolution of the vortex pair formed by the jets depends on the spanwise positions of the yawed jets relative to the direction of the free stream and their spanwise interactions are affected by the jets relative yaw angles, resulting in varied topologies that range from a fully coalesced single vortex to a pair of weakly interacting vortices. It is also shown that the interaction of the two jets can lead to a nearly uniform spanwise momentum flux recovery that within the present parameter range is up to 50% of the boundary layer momentum flux deficit at 100 equivalent diameters downstream from the jets’ orifices.