الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Local scour downstream of irrigation works is one of the important and complicated problems facing many of hydraulic engineers. So the estimation of geometric characteristics of scour hole occurring downstream of hydraulic structures is a topic of strong importance, that occurs downstream of irrigation structures to protect them from failure. Stilling basins are employed downstream of hydraulic structures to dissipate the kinematic energy resulting from the hydraulic jumps and to control the downstream scouring. To study local scour downstream a radial gate under different operating cases, an experimental investigation was carried out. The radial gates are considered one of the most common water control structures in many irrigation networks that are used for many purposes. One of the main purposes of radial gate is to measure and control the discharge of open channels, also, they are used to control the water levels and to generate power. They may be operated under free or submerged flow depending on the tailwater depth.
Hundred and eighty experimental tests were conducted in the irrigation and hydraulics laboratory, Benha Faculty of Engineering, Benha University. The experimental program was carried under submerged flow conditions. Experimental model with five discharge was used. Five operating cases of gates were considered according to the number of the opened gates with different arrangements. The considered parameters were Froude number, upstream water head, gates opening, tailwater depth, and using four heights of natural roughness elements and three U-shaped corrugated beds on the stilling basin under submerged flow conditions produced by radial gates. The verification procedure has been conducted by achieving a comparison between the experimental measurements and that predicted by the simulation model.
The present study aims to improve the characteristics of submerged hydraulic jumps, control and minimize the local scour downstream the radial gates. All the experimental results were analyzed and discussed. The relationships between all characteristics of submerged hydraulic jumps, the maximum relative scour depth and length ds/y1, Ls/y1 were presented versus the Froude number (Fr1), submergence factor S, and relative roughness heights ks/y1.