Abstract This paper deals with a new compound broad crested weir for measurement of discharge. Calibration of broad crested weir is mainly dependent upon the length of the weir crest (L), weir height and upstream water head over weir crest (h). Hence measurement of discharge varies as per change in the flow characteristics due to change in the geometry of weir for a given flume. Based on experimental analysis, past researchers have shown that discharge coefficient (Cd) changes proportionally with h/L ratio, maintaining an average range of Cd for various h/L values. In the present study a novel approach towards design of compound broad crested weir is proposed which can effectively measure wide range of discharges thereby maintaining a constant discharge coefficient irrespective of the head over weir. Experimentation has been carried out in a laboratory horizontal tilting flume 2.5 m long, 20 cm wide and 30 cm deep. The investigation is carried out for discharge ranging from 10 lps to 2 lps. In the earlier experimentation conducted Cd was varying in the range from 0.518 to 0.648, after which the broad crested weir model is modified for suiting best results thereby resulting in the reformed discharge coefficient values of 0.546–0.599 which is in close proximity to the design input value of 0.6.

中文翻译：

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复合宽顶堰流量测量试验研究

摘要 本文研究了一种用于流量测量的新型复合宽顶堰。宽顶堰的标定主要取决于堰顶长度（L）、堰高和堰顶上游水头（h）。因此，由于给定水槽的堰几何形状的变化，流量的测量随着流量特性的变化而变化。根据实验分析，过去的研究人员表明，流量系数 (Cd) 随 h/L 比成比例变化，从而在不同 h/L 值下保持 Cd 的平均范围。在本研究中，提出了一种设计复合宽顶堰的新方法，该方法可以有效地测量大范围的流量，从而保持恒定的流量系数，而不管堰上的水头。实验是在实验室水平倾斜水槽中进行的，该水槽长 2.5 m，宽 20 cm，深 30 cm。调查是针对 10 lps 至 2 lps 的排放量进行的。在早期进行的实验中，Cd 在 0.518 到 0.648 的范围内变化，之后宽顶堰模型被修改以适应最佳结果，从而导致改革后的流量系数值为 0.546-0.599，与设计输入非常接近值为 0.6。