Characteristics and Hazards Analysis of Vortex Shedding at the Inverted Siphon Outlet

Abstract

This paper studies Karman vortex shedding and water-level fluctuation in the inverted siphon structure of the Middle Route of the South-to-North Water Diversion Project (MR-SNWDP) in China. Field investigations and numerical simulations for the inverted siphon outlet were performed to explore the characteristics and hazards of the vortex. Numerical results were compared with measured data to verify the effectiveness and reliability of the model. Based on the model, it is found that the periodic water-level fluctuations caused by the Karman vortex street will not only excite surges to beat the gate but will also induce periodical force on the gate pier. Those will damage the building structure and affect the delivery capacity in the long-term operation. Based on this, countermeasures of altering different pier tail shapes are proposed to control vortex shedding, and the effect is noticeable. The study presents a hydraulic process for the inverted siphon outlet and provides a theoretical reference for water delivery safety of inverted siphons and similar structures in MR-SNWDP.