Research on Shape Optimization and Eddy Reduction Effect of the Cylindrical Pier in Large-Scale Water Diversion Open Channel
Amounts of cross-channel bridges have been built in long-distance large diversion channels,and the accumulation of the flow resistance caused by the numerous piers will inevitably increase the flow energy loss.In order to increase the water transfer capacity of the water transfer project,it is necessary to investigate the flow characteristics around the channel piers and the drag reduction measurements.Taking the cylindrical pier across a large water conveyance channel as the research object,the hydrodynamic characteristics of the pier are researched on basis of theoretical analysis and hydrodynamic numerical simulation.By analyzing the characteristics of cylinder flow,the boundary of the main region of the wake vortex and the shape curve function are obtained.Considering the effect of turbulent energy dissipation and the engineering application,a new shape type of fish-shaped pier with a sharp head and a streamlined tail is proposed.By adopting the factors of velocity,pressure,turbulent kinetic energy and vortex intensity,the flow characteristics of the cylindrical pier and the fish-shaped pier and their differences are analyzed based on 3D flow simulation data,and the drag reduction mechanism of the fish-shaped pier is indicated.The research shows that the fish-shaped pier contributes to vortex elimination and turbulence suppression.Comparing with the cylindrical pier,the turbulent energy dissipation is reduced by over 55％,the vorticity attenuation is up to 53.3％～84.8％,and the drag reduction effect is more than 30％.In the test application used in large-scale channel,the head loss of the fish-shaped pier was reduced by 64％,which verified the scientific and practical as well as the effect of vortex dissipation and drag reduction properties of the new shape type of the cross-channel pier.
cylinder flowpier across canalwake vortexturbulent kinetic energystreamlinefish-shaped pierdrag reduction effect
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