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Determination of Small Discharges of Water by Triangular Notch Thin-Plate Weirs
Pospíšilík, Šimon ; Havlík,, Aleš (referee) ; Šoltézs, Andrej (referee) ; Zachoval, Zbyněk (advisor)
The work deals with the determination of relatively small discharges of clear water using a thin-plate weir with a triangular notch. Based on a detailed search of contemporary knowledge, the scope of the necessary experimental research was defined in the range of parameters practically suitable for the determination of small discharges. It was about extending the range of notch angles by small angles, defining the minimum weir height depending on the notch angle, determining the influence of the minimum value of the weir height and the width of the approach channel on the discharge and investigating the effect of water temperature on the discharge. Extensive experimental research was carried out involving changes in the notch angle, head, weir height, approach channel width and water temperature. The uncertainties of the measured data were quantified. By analysing possible ways of expressing small water discharges using thin-plated weirs with a triangular notch and based on the measured data, a new equation for determining water discharges was recommended as the most suitable. The new equation combines the Kindsvater-Shen approach, which captures the cumulative effects of viscosity and surface tension, and the approach of covering the effect of the relative width of the approach channel by introducing a new coefficient. By evaluating the measured data, the effective discharge coefficient, the relative width of the approach channel coefficient, the effective head and the limit head were determined in the newly proposed equation. The uncertainty of the determination of the effective discharge coefficient was quantified. Verification of the new equation was carried out by comparing the values calculated by the new equation and the values measured by other authors. The work extended the application possibilities of thin-plated weirs with a triangular notch in determination of small discharges of water and extended the knowledge of weir behaviour.
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