挟沙水流悬移质运动效率系数的研究

悬移质运动效率系数是泥沙悬浮运动消耗能量(悬浮功)与挟沙水流紊动能量之比值,它是反映悬移质运动能量功效最重要的特征参数.本文基于两相挟沙水流紊动能量平衡方程,在二维、恒定、均匀及充分紊动的流态条件下,经过必要的推导和简化,得出悬移质运动效率系数理论表达式;通过应用黄河下游实测资料,对效率系数公式进行验证计算,结果表明效率系数公式计算值与实测值相符较好;进一步应用黄河下游实测资料,建立了效率系数与水流挟沙能力之间的关系,说明随着含沙浓度的增加,水流挟沙能力相应加大,效率系数呈下降趋势,并趋于一个稳定的低值范围,含沙浓度进一步增加不会给水流增添额外的能量负担,为黄河挟沙水流高效输送提供了科学依据;同时效率系数公式的导出为建立挟沙水流挟沙能力公式、揭示输沙机理奠定了基础.

Study on Efficiency Coefficient of Suspended Load Motion in Sediment-laden Flows

An efficiency coefficient of suspended load motion is defined as the ratio of the suspended power to turbulent energy in sediment-laden flows, which plays important role in the studies of sediment transport capacity as a significant parameter of energy power efficiency in suspended load motion.According to the equilibrium equation of turbulent energy in sediment-laden flows, under the conditions of two-dimensional, steady, uniform and sufficiently turbulent flows, a new expression of the efficiency coefficient of suspended load motion has been achieved by means of essentially theoretical derivation and simplification. Using the filed data from the Lower Yellow River, the expression of the efficiency coefficient was better verified. It has been indicated by establishing relation between the efficiency coefficient and comprehensive index for sediment transport capacity that the increasing of concentration does not add supererogatory energy burden while the sediment concentration is more, and which has significance for planning of the more efficient sediment transportation engineering in the Yellow River.