| 摘要: |
| 【目的】探索含沙量变化对U型渠道挟沙水流垂线流速分布的影响，进而从理论上完善挟沙水流流速分布规律。【方法】通过U型渠道水槽试验，测定水流中含沙量为1.12～500 kg/m3时，最大流速所在位置的变化，同时引入卡门常数κ，来反映含沙量对垂线流速分布的影响。【结果】当水流含沙量s<300 kg/m3时，随着含沙量的增加，最大流速点的位置逐渐下降，在主流区、底流区和表面区，挟沙水流均遵循对数流速分布规律，但κ的变化规律不同；当含沙量s≥300 kg/m3时，水流的流型发生了变化，表面区、主流区水流不再遵循对数流速分布规律，底流区虽仍遵循对数流速分布规律，但κ的变化规律与s<300 kg/m3时不同，κ的变化趋势总体随着含沙量的增大而减小。【结论】U型渠道挟沙水流遵循对数流速分布规律，κ的变化规律与普通明渠不同，应该分别对待。 |
| 关键词: U型渠道 含沙量 卡门常数 挟沙水流 流速分布 |
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| 基金项目:国家“十一五”科技支撑计划项目（2006BAD11B03） |
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| Effects of change of sediment concentration on vertical velocity distribution in U-Channel |
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| Abstract: |
| 【Objective】The experiment was done to search for effects of change of sediment concentration on vertical velocity distribution in U-Channel,thus theoretically to perfect velocity distribution of sediment-laden flow.【Method】We surveyed change of the location of maximum velocity when the sediment concentration was 1.12-500 kg/m3 in flow by the flume experiments in U-Channel.At the same time,introducing Karman constant κ was to reflect effects of change of sediment concentration on vertical velocity distribution.【Result】With sediment concentration s<300 kg/m3,as sediment concentration increased,the location of maximum velocity point decreased.Sediment-laden flow followed logarithmic law of velocity distribution at main-flow area,bottom flow area and surface area, but variation of κ was different.With sediment concentration s≥300 kg/m3,flow pattern changed,except that sediment-laden flow followed logarithmic law of velocity distribution at bottom-flow area,sediment-laden flow didn’t follow logarithmic law of velocity distribution at surface area and main-flow area,and variation of κ was different from sediment concentration s<300 kg/m3 at bottom-flow area.The general trend of κ reduced with the increase of sediment concentration at bottom flow area.【Conclusion】Sediment-laden flow follows logarithmic law of velocity distribution in U-Channel,compared with common channel,variation of κ is different and should be treated separately. |
| Key words: U-Channel sediment concentration Karman constant sediment-laden flow velocity distribution |
