Experimental Investigation of Convecting Vortex/Boundary-Layer Interactions

摘要

The interaction between propagating spnnwise vortices and a turbulent boundary layer was studied experimentally. The results focus on the relationship between the passage of vortex structures and the response of the boundary Inyer In terms of ensemble-averaged unsteady mean velocity, wall shear, and turbulent stresses. Both positive and negative circulation vortices were studied at different heights above the test surface. The results indicate Hint the sign of the vortex has an effect on the wall shear response as well as the height of the vortex above the surface. The negative circulation vortices were found to interact more closely with and penetrate deeper into the boundary luyer than the positive sense vortices. A phase lag between the freestream disturbance caused by the vortex and the wnll shear stress response is demonstrated. The relationship of the measured wall-shear stress to the pressure gradient and to a scaling velocity determined from the standard log-law fit for the overlap layer are discussed. The response of the boundnry-iayer turbulence is examined at key phases during the interaction.