Abstract The flow characteristics of the hydraulic jump due to parallel jets are different from the classical jump emerging from a single gate. Due to the highly complex flow field at the downstream pool, deciding about the tailwater measuring location is a challenging issue affecting the flow measuring accuracy. Experiments are conducted herein, on different parallel jets’ configurations for both free and submerged flow conditions. To quantify the flow uniformity, for any downstream cross section, the associated momentum correction factors, β2, were estimated for the free-flow condition. It is found that β2-values depend significantly on the measuring location, and consequently the available conjugated depths relationship results in poor estimation when measuring location moves downstream. Employing Buckingham analysis, a general formula is proposed to calculate the momentum correction factors associated with the free hydraulic jump at different downstream measuring locations. The experimental results of this study indicated that such a formula enhances distinguishing between free and submerged flow conditions of the gates installed in parallel. Finally, a dimensionless stage-discharge formula is presented to predict the submerged flow rate through parallel gates of different gate openings and widths.

中文翻译：

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自由和水下多射流的实验研究

摘要 平行射流引起的水跃的流动特性不同于单门水跃的经典跃迁。由于下游水池流场高度复杂，尾水测量位置的确定是影响流量测量精度的一个具有挑战性的问题。在本文中，针对自由流动和浸没流动条件的不同平行射流配置进行了实验。为了量化流动的均匀性，对于任何下游横截面，相关的动量校正因子 β2 被估计为自由流动条件。发现 β2 值显着依赖于测量位置，因此当测量位置向下游移动时，可用的共轭深度关系导致估计不佳。采用白金汉分析，提出了一个通用公式来计算与不同下游测量位置的自由水跃相关的动量校正因子。本研究的实验结果表明，这样的公式增强了对并联安装的闸门的自由和潜流条件的区分。最后，提出了一个无量纲阶段-排放公式来预测通过不同闸门开口和宽度的平行闸门的淹没流量。