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<p>The Crump weir is widely used for measuring flow rates in irrigation channels with both steady and unsteady flow. In this study, the calibration of the discharge coefficient of the Crump weir under conditions of free flow with increasing flow rates was empirically investigated through four different flow-time patterns. The flow-time patterns were considered incrementally over various durations. Experimental tests were conducted in a research flume, equipped with a data recording device, measuring 10&#xa0;m in length, 0.80&#xa0;m in width, and 1.20&#xa0;m in height. The Crump weir was installed 5.50&#xa0;m from the start of the channel. According to the conducted experiments, the behavior of the flow discharge coefficient over the Crump weirs is presented based on dimensionless parameters across different patterns and ranges. Various weirs with different heights and upstream and downstream angles were also utilized. The results indicate that the flow discharge coefficient in the presence of flow rate variations has an inverse relationship with the dimensionless parameter of flow depth upstream of the weir crest relative to the weir height, generally leading to a decrease in the discharge coefficient. In the final step, optimization of the discharge coefficient was performed using a genetic algorithm. The results show that the calibrated discharge coefficient in free flow conditions, despite variations in flow under different patterns, ranges from 0.6 to 2.0.</p>

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Investigating the Discharge Coefficient in Crump Weirs Under Increasing Flow Rate Conditions (Unsteady Flow)

  • 期刊论文

  • 发表日期：

    2025年7月30日

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  • Mohammad hasan Hashemi Fesharaki,
  • Ali Khoshfetrat,
  • Elham Izadinia,
  • Ehsan Delavari

摘要

The Crump weir is widely used for measuring flow rates in irrigation channels with both steady and unsteady flow. In this study, the calibration of the discharge coefficient of the Crump weir under conditions of free flow with increasing flow rates was empirically investigated through four different flow-time patterns. The flow-time patterns were considered incrementally over various durations. Experimental tests were conducted in a research flume, equipped with a data recording device, measuring 10 m in length, 0.80 m in width, and 1.20 m in height. The Crump weir was installed 5.50 m from the start of the channel. According to the conducted experiments, the behavior of the flow discharge coefficient over the Crump weirs is presented based on dimensionless parameters across different patterns and ranges. Various weirs with different heights and upstream and downstream angles were also utilized. The results indicate that the flow discharge coefficient in the presence of flow rate variations has an inverse relationship with the dimensionless parameter of flow depth upstream of the weir crest relative to the weir height, generally leading to a decrease in the discharge coefficient. In the final step, optimization of the discharge coefficient was performed using a genetic algorithm. The results show that the calibrated discharge coefficient in free flow conditions, despite variations in flow under different patterns, ranges from 0.6 to 2.0.