Study On Passive Flow Control Of Flow Around Stay Cables

Wind-induced vibration of stay cables is a great concern to the bridge engineering community. Wind-induced vibration is caused by unsteady vortex shedding in the near wake of the cable. To suppress the unsteady flow around the cable, this thesis proposed three flow control methods: cylinder with slots, ring with self-suction and self-blowing holes, helical rings.In this paper, PIV technique was employed in wind tunnel tests to investigate the control effects and influencing factors of flow around a cable model.Firstly, flow characteristics, including time-averaged streamline, velocity and Turbulent Kinetic Energy (T.K.E), around the cable without control was studied. Swirling strength was adopted in this thesis to characterize the strength of vortices and flow transportation;Secondly, flow structures around the cable with slots were studied. The flow suppression mechanism were analyzed and the control effects of the cylinder with different slots were studied.Thirdly, a group of rings with self-suction and self-blowing holes were equipped on the cable surface to suppress the unsteady flow around the cable, then the rings’ pitch effect on flow control were studied;Finally，a type of helical ring was proposed to suppress the flow around the cable, then the height effect and pitch effect on flow control were both studied.