| Abstract: |
Experimental and Theoretical studies were carried out to investigate a suitable stilling basin down stream DROP structures to dissipate energies through the formed hydraulic jump. Two cases were studied in a rectangular section, one of them was a model for one DROP structure, and the other one was a model for two consecutive DROPs.The different characteristics of flow downstream DROPs were studied under the effect of end sill with different heights, and baffle blocks with different heights and positions. Experiments were carried out within certain range of Froude number.The theoretical study depend on the basics of dimensional analysis to obtain a dimensionless parameters to correlate the different relationships between the different variables, which affect the flow characteristics, such as, depth ratio of the jump, length of the hydraulic jump, and the energy loss through the basin.7.2 conclusions:7.2.1 For One DROP:1- The relative water depth, and the relative energy loss was increased with the increase of Froude number in the range between (2.5-5.00) in the cases of flat surface downstream DROP, presence of end sill and presence of baffles blocks.2- For the flat basin case the relative water depth was increased with the increase of relative DROP height in the range between (W/y1=3.0 to 10.0), while the relative energy loss was decreased with the increase of the relative DROP height within the same range.3- The presence of end sill increased the relative energy loss and decreased the relative water depth by small values ranged between (3% to 5%).4- The relative water depth was decreased with the increase of the relative height of the baffles, while the relative energy loss was increased in the range of Froude number between (1.15-5.00).5- The optimum location of the baffles was found to be at 60% of the basin length or at approximately at (L1/y1 = 7.75 to 8.50).7.2.1 For Two DROPs:1- Presence of end sill at the end of upper basin affect greatly upon the hydraulic performance of the two basins.2- The relative energy loss, and the relative water depth were increased with the increase of Froude number for all cases ( no end sill, or presence of end sill, or presence of baffles blocks).3- The relative energy loss in the upper basin was decreased with the increase of relative end sill height at the end of the upper basin, while the relative energy loss within the lower basin was increased as well.4- The relative water depth was increased with the increase of the relative height of the end sill at the end of the upper basin.5- The relative water depth was decreased with the increase of the relative end sill height at the end of the upper basin.6- The presence of end sill at the end of lower basin did not affect upon the hydraulic performance of the upper basin.7- Presence of the end sill at the end of lower basin had a small effect on the hydraulic performance within that basin, while its presence was useful for localizing the hydraulic jump.8- The relative energy loss was increased with the increase of the relative height of the baffles within the range of study.9- The optimum location of baffles was found to be L1`/LB=0.5 when Froude number F1>1.17, and L1`/LB=0.6 when Froude number F1<1.17.10- The optimum relative height of the end sill was found to be Se1/y1=(0.89-1.35) in case of using two successive DROPs.7.3 Recommendations For Future Studies:There are some suggested recommendations and future studies that may be considered, like the following;1- Using different shapes of end sill and its effect on the performance of two successive DROPs need more investigations.2- Applying different shapes of baffles blocks are recommended to be investigated as well.3- It is recommended to study the different ratios of DROP heights.4- It will be desired to investigate the effect of the suggested types of stilling basins and corresponding scouring activities downstream such structures.5- Studying the effect of bed slope on the hydraulic performance through the basin worth to be investigated too.6- Building numerical models to be able to predict the different characteristics of flow performance downstream such DROP structures are recommended also.
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