Hydraulic Characteristics of Square Labyrinth Weirs with Sharp or Semi-Circular Crest

Labyrinth weirs have been of interest to engineers and researchers for many years because of their hydraulic behavior. This paper present an experimental study to define the hydraulic characteristics of flow over square labyrinth weirs with semi-circle and sharp crest, by using range of experiments. and compare their efficiency with conventional weirs( Suppressed rectangular weir) with same shape of crest, three different heights (p) for each one of these weirs were used ( 25,20 and 15 ) cm for  each of the above cases , seven different discharge were passed. The overall tests in this study were  84. Data obtained from laboratory and according to the result parameters from the dimensional analysis of the factors affecting on the flow over the labyrinth weirs, parameters were plotted, it was found that the  labyrinth weirs gave better performance efficiency when compared to conventional weirs(Suppressed rectangular weir) for their passage  and capacity  high discharge. Also the results show that the  coefficient of discharge (Cd)  with constant  height  of  weir have a high value  in low values of  H/P and decrease  gradually with increase this ratio , where gave the square labyrinth weirs with semi-circle the highest value of the discharge coefficient reached (2.55) . In additional to shape of crest weir has great  effect on (Cd) and on performance efficiency , where the labyrinth weir  with  semi -circular crest gave high performance from  sharp crest.