Study On The Navigable Flow Conditions Of Under Approach Channel Of The Curved Reach

Affected by the project layout,filling water from the Hub,the boundary conditions of curved reach,the characters of bending flow and so on,the flow condition is very bad when the approach channel is near the sluice gate.The flow condition of the approach channel in the downstream is restricted by the sideling flow that is produced from the expansion section,the circumfluence that is produced between the river and channel,but also affected by the bending water.The energy of reflux and oblique nearby the entrance area of downstream approach channel is great,the range is large,the flow condition is difficult,the navigable flow condition will be difficult to meet the requirement of safe navigation.The downstream water is seriously influenced by the discharged water even if the water release from Dam is small.For the reason is that the water level between upper and lower reaches is large,the water depth of downstream is small.At this time,transverse and reflux appear at the entrance area.The flow conditions will be more bad with increasing water release.It is because that the power of flow and the velocity are bigger and the effect from the boundary condition is bigger.The influence of flow condition by the water release at the entrance area will be larger.The river will be recovered as the natural state for the low head projects when the flow is enough and the sluice gates are all opened.At this time,the characteristic of bend flow is outstanding that will bring some problems of flow for the entrance area.In a word,the navigation flow condition of the entrance area is bad whether the flow is big or small and threats the navigation safety of ships.In order to remove the harmful effects of flow condition at the downstream entrance area and ensure the safety of ship navigation,the paper puts forward the comprehensive regulation measures that open-type guide wall,the continuous navigation wall and the piers for deflecting flow which are built outset of the end of the guide wall are erected at same time.The results had been validated based on the mathematical model test and integrated physical model test of XiaoXiang Hydropower Station dam.The flow direction was adjusted after built the comprehensive regulation measures.And the disturbing place of river by the measures was outside of the scope of navigation channel.At the same time,the piers blocked the flow,strengthened the turbulent of the flow,weakened the power of waterbody.By this way the flow becameslow,the water area of slowly flow was constructed,the reflux and oblique were completely eliminated,the navigable flow condition was improved,and the require of safety of ship navigation was satisfied as much as possible.It was novel that adjusts the navigation flow condition by the piers for deflecting flow.So as to increase the applicability of it,the paper built mathematical conceptual model.By the model the paper researched the relationship of the horizontal distance between the piers and the guide wall and the maximum velocity in the outlet area of approach channel for ship gate.The result offered a reasonable option of plane position for the pier.