Experimental Study for Energy Dissipation Using Stilling Basin with One and Two Consecutive Drops

Abstract

The scour at downstream of hydraulic structures is one of the major concern in its stability analysis and operation .The excess energy existing immediately downstream of such structures has to be controlled. Hence, it is necessary to design and install a device for dissipating excess energy in order to prevent downstream scour. The drop structures is one of the commonly structures used for dissipating excess energy.
In the present study an experimental approach is employed through which different types of stilling basin with different heights were tested using one drop and two consecutive drops. Moreover the effect of the end sill and baffles with different heights and different bed slopes was investigated. The hydraulic parameters involved were measured experimentally using a model of straight drop installed in the available (S6) multi-purpose flume in the fluid mechanics lab at the Civil Engineering Department, University of Garyounis.
Results showed that, for one drop the presence of end sill reduced the length of the jump by a small value approximately 4%with an increase of relative energy loss by a small value. The increase of relative baffles block height increases the optimum relative height of drop (w/y1=6), and the relative energy loss .For two consecutive drops it was found that the most value of energy loss takes place in the second basin. The presences of end sill at the end of second basin increases the performance of second basin by small value approximately 5%. It is also shown that increasing the relative height of baffles blocks lead to increases in the relative energy loss (within the ranges considered in this study), and the optimum relative baffle block height hb/y1=0.77 to 1.7 and bed slope is 1/50