الفهرس 
AcknowledgmentsOnly 14 pages are availabe for public view
 |  | from | 231 |  |  |
| | | from | 231 | | |
Abstract
Spillways usually used for escaping water from the U.S. side, having a
high-water level, to D.S. side, having a low water level in most of the
diversion head structures through water streams. The D.S. of such
spillways usually suffers from the destructive impacts of the generated
kinetic energy of the flowing water, having a very high speed, which may
cause cavitation in such spillways body.
The present work is introducing some geometrical treatments on the D.S.
side of the spillway body, aiming to increase its efficiency in dissipating
the kinetic energy of the flowing water, having great potential energy, and
improve the flowing water quality by increasing its dissolved oxygen
content, through generating huge aeration at the flow in the D.S. side,
also, to prevent cavitation, which may occur, and generated on the surface
of the spillway body, and protecting its safety. Literature proved that the
stepped spillway body is one of the most practicable trails done for
achieving the above-mentioned goals.
The experiments were carried out in the Irrigation and Hydraulic
Laboratory, Faculty of Engineering, Assiut University, Assiut, Egypt,
using 21 tested spillway models, including different types of steps, with
different ratios between their height, and width, for reaching the most
suitable number of steps, and the optimum relative ratio between their
heights and width. The obtained optimum number, shapes, and relative
dimensions of the tested steps were examined using the available
laboratory discharges ranged from 2.52 l/sec, to 19.12 l/sec (Upstream
Froude number ranges from 0.01 to 0.08), for studying their impacts on
the water-energy dissipation, and dissolved oxygen content as a water
quality indicator.
Abstract
(iii)
The study proved that, the step height to step length ratio (h/l) equals 0.50,
and step height to spillway height ratio (h/H) equals 0.20 are the optimum
dimension for improving the water-energy dissipation and flow aeration.
Also, the present study proved that the reverse inclined step and quarter
circular end sill enhance the water-energy dissipation and flow aeration
more than the straight steps, where the length of reverse step to the step
length ratio (lr/l) equals 0.25 can be taken as the optimum ratio. Radius of
end sill to step height ratio (r/h) equals 0.40 gives the maximum energy
dissipation and maximum dissolved oxygen content compared to the other
ratios