الفهرس 
chapter 1Only 14 pages are availabe for public view
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Abstract
Upstream storage dams, the water makes a large storage area where excess water crosses the dam through its spillway to the river basin. The
generated large potential energy causes scour in the spillway basin and in the
water way downstream the dam. On the other side, the transfer of water from
the large storage area to the narrow basin may lead to convergence of the
water way through the spillway or the basin. So this study aims to dissipation
of this energy to protect the water way from scour and studying the effect of
the convergence on the energy dissipation and other characteristics of
Hydraulic jump.
Firstly, different contraction ratios were tested for the same angle of
conversion. It was found that conversion decreases energy dissipation and
increases the jump length and the tail water depth. For a constant width
(b=21cm) which gave the minimum energy dissipation, the effect of changing
the convergence and entrance angles were studied. The convergence angles
less than or equal 130 are the best angles for the energy dissipation point of
view. Half cylinder strips were placed on the sloped back of the studied model
to dissipate energy. The effect of changing the number, position and
diameters was studied. For practical, the rectangular strips were used instead
of half cylinder strips. It was found that the half cylinder strips are more
effective in the energy dissipation. The effect of stepped spillway as the most
common spillway was studied. To verify the results, a one dimension
momentum equation was used to derive theoretical equation for the tail water
depth.
It was found that the best case of half cylinder dissipate energy by
1.1 times the case of stepped spillway and 1.2 times the case of sloped back
without strips for the same flow condition. The theoretical results were found
to be in a good agreement with the experimental data. Finally, the results of
this study may be recommended in the field of applications.