Effect of shape and size of end sill on hydraulic energy dissipation behaviour in inclined spillway
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Date
2015-06
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
In this study laboratory experiments were conducted to observe hydraulic energy dissipation behaviour through the formation of hydraulic jump in an inclined spillway with SAF stilling basin using different shapes and sizes of end sill for varying discharge conditions. In all cases the total drop was kept constant. The observation were recorded using different combinations of height and shapes of end sill such as rectangular end sill (RES), triangular end sill (TES), semi-circular end sill (SCES), diagonal vertical upstream end sill (DVUES) and diagonal vertical downstream end sill (DVDES). These end sills were used for three heights of 3 cm, 4 cm and 5 cm at selected discharges of 1.65 lit/sec, 4.4 lit/sec, 4.9 lit/sec and 5.5 lit/sec respectively. Required flow parameters like pre and post jump depth of flow, height of jump were experimentally observed for 60 different combinations of end sill shape, discharge and height of end sill. Based on these observations, pre and post jump flow energy was determined and accordingly amount of relative loss of energy, hydraulic jump efficiency were calculated and compared. It was observed that in case of triangular shaped end sill, the maximum relative loss of energy occurred in 07 combinations of end sill height and discharge out of total 12 combinations tried and in no case it provided the minimum energy loss. Similarly, semi- circular, rectangular and diagonal vertical downstream shaped end sill provided minimum energy loss in 4 cases out of 12 combinations tried for each while each of them provided maximum energy loss only in one case. The diagonal vertical upstream shaped end sill provided maximum and minimum relative energy loss in only one case each. It was also found that the triangular shaped end sill resulted in minimum height of jump, in general, for different combinations of height and discharge.
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