隧洞尾部带加压板弧形闸门水流垂向收缩特性

Investigation on hydraulic vena contracta of radial gate for closed conduit with roof panel

为了分析压力隧洞尾部弧形闸门出口水流的垂向收缩特性,采用水流带动彩线的试验演示和测量压力隧洞弧形闸门处的水流特性.试验测量不同开度下的水位流量关系,获得不同开度和水位情况下弧形闸门的收缩系数,以及收缩系数与开度、水位的关系.利用量纲分析和回归拟合获得了收缩系数与开度和水位的近似方程.结果表明,压力隧洞尾部弧形闸门的出闸水流收缩程度较明渠无压弧形闸门的小,收缩系数随着开度的增大而先减小后增大,而随上游水位的变化趋势不明显.拟合的收缩系数公式能够较好地计算压力隧洞尾部带加压板弧形闸门的水流收缩系数.

In order to analyze the vertical contraction of the outflow through radial gate, a hydraulic experi- ment was conducted. The flow characteristics were investigated through various color threads distributed in the flow field. The experiment presented the contraction coefficients for various situations of gate open- ings and water levels by measuring the corresponding discharge. Then the relationship of the contraction coefficient, gate opening and water level was analyzed. Consequently an approximate formula was sugges- ted by the dimension and regression analysis. The results show, the hydraulic contraction of the radial gate with roof panel in closed conduit is smaller than that one in open flow. The contraction coefficient increases at first and then decreases with the increase of the gate opening, but it changes slightly with the water level. The proposed approximate formula proposed can reasonably calculate the contraction coefficient for the radial gate with roof panel in closed conduit.