Experimental Research On The Interaction Between Streamwise Vortex And Surface

Vortex,as a common flow phenomenon,plays an important role in fluid motion.Examples of the interaction between vortices and surfaces are also common in aircraft,wind engineering and other applications.It has not only important academic value,but also considerable engineering application prospects to study the fluid problem of the interaction between vortices and surfaces.This study focuses on the interaction between the streamwise vortices and the surface,and explores it from two aspects: mechanism research and practical application.In the aspect of mechanism research,based on the physical model of the interaction between a single streamwise vortex and the surface of a plate,the near-wall flow field structure is analyzed by using oil flow visualization technology;the pressure distribution of the surface and spatial flow field characteristics are also obtained,and the cause and manifestations of the secondary vortex are analyzed;furthermore,the interaction between a vortex pair in which the two vortices rotate in opposite directions and the surface of a plate is analyzed,and the interaction process is divided into two stages: the vortex-vortex interaction stage and the vortex-wall interaction stage.The flow rules in each stage are summarized.Finally,the practical engineering application of the interaction between the streamwise vortex and the surface is completed on the research platform of a flow tube with the pressure gradient and the research platform of the double delta wing with a large sweep angle.The results show that: there is not only the "image effect" in the interaction between a single streamwise vortex and the surface of a plate,but also an off-wall motion in the vertical direction,and a new secondary vortex structure is generated in the interaction process.For a vortex pair in which the two vortices rotate in opposite directions and have different vorticity,the weaker vortex will be entrained by the stronger vortex,and the interaction between the two vortices will be significantly affected by the magnitude of D.The streamwise vortex can eliminate the deceleration zone in the flow tube with a pressure gradient,and the intensity and spatial position of the streamwise vortex will be changed by the flow tube.The vortices over the double delta wing with a large sweep angle can be effectively controlled by a tip perturbator and generate controllable rolling moment.