الفهرس 
Objectives of the studyOnly 14 pages are availabe for public view
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Abstract
Local scour downstream control structures may cause damage or complete failure of the control structures. The objective of this research is to investigate the influence of using semi-circular baffle blocks upon the characteristics of a hydraulic jump as energy dissipater and consequently upon the expected scour hole downstream a control structure.
Hundred and eighty nine experimental runs were carried out in the Irrigation and Hydraulics laboratory, Faculty of Engineering, Minufiya University. Two cases of baffle block arrangements were included. The two cases were considered, double line baffle blocks at different positions, and fully baffled floor.
Different heights of baffle blocks were tested in these two cases under different flow conditions. It was found that, all suggested arrangements of baffle blocks caused noticeable reduction for the maximum scour depth and length, while they tend to move the location of maximum scour depth closer to the floor.
It was noticed that, the case of fully baffled floor gave more reduction of maximum scour depth for most of the used flow conditions. While, the cases of double line baffle blocks gave more reduction of scour hole length for all used flow conditions.
Baffle block with their heights and arrangements had significant effect on the scour hole profile. Empirical formulas were developed for estimating scour hole dimensions in terms of downstream flow conditions, involved dimensions, according to various arrangements of the baffle blocks, including the case of no baffle blocks.
Clearly, all suggested baffle block arrangements under the tested flow conditions, control the hydraulic jump location within the stilling basin upstream of the baffle blocks. whereas they increased the sequent water depth of the hydraulic jump more than that of the case of no baffle blocks.
Experimental results showed that, the height of baffle blocks had significant effect on hydraulic jump height, while baffle blocks position had noticeable influence on the hydraulic jump location. It was concluded that, the fully baffled floor dissipated the excess energy through the hydraulic jump approximately equals to that of the double line baffle blocks. Empirical formulas were developed for estimating the sequent water depth in terms of height and arrangement of the baffle blocks as well as the tail flow conditions.