Flow And Sediment Transport Characteristics Around Suspended Curtain Of Harvesting Bedload

Along with the development of our national economic and the reinforcement of the ability of protecting environment, diversified methods for controlling the sediment having taken effect gradually, and the large-scale water conservancy measures having been constructed, etc. the sediment amount which runs to the ocean from the big rivers like the Yangtse River, the Yellow River etc. has been dramatically reduced and the countermarch phenomenon of coastline is speeding up. Nowadays, there are lots of measures for deposition promotion and erosion control, in addition to the ecological measures, dikes, vanes and many others are widely used.This paper presents a new kind of apparatus for harvesting sediment in flows which is termed as a suspended curtain or harvesting sediment. The curtain was a piece of rectangular sheet,which was shin and light weight. One side was fixed to the bed with a heavy pillar. A rectangular window was opened near the side close to the pillar. This window, termed as sediment-passing-window, allowed moving sediment passing through and reduced the drag force on the curtain exerting by the flow. The pillar was laid onto the bed, which was stable against pulling away by the flow. The curtain diverted the flows to upside, and in the lee of the curtain formed a big and a small flow circulations, and the sediment particles which passed through the sediment-passing-window was filled up in the flow circulation area, accordingly, the aim to trap sediments was achieved. The characteristics around the suspended curtain were investigated in the two dimensional flume which was 1 m wide. A new method to achieve the flow field- simple PIV method was proposed. How the factors such as velocity of flow, the height of curtain and so on affect the slope angle of curtain and the effective height of curtain were investigated. The factors for the flow circulation size of the curtain, the best height of curtain and the best spatial layout between the curtains were also investigated. A function about the slope angle, velocity and relative height of curtain were also drawn up. Finally, preliminary experiments on the movable bed were carried out, and the characteristic of the sediment deposition around the suspended curtain were explored.Compared to the dikes, groins, the device has lots of advantages, such as low cost, quick-acting, simple-constructing, little-disturbing and little-resistance for the flow, and removing convenience. It can be applied to the deposition promotion projects for protecting the beach or bank erosion control.