Experimental Study of Scour Downstream Piano Key Weir Type C with Changing Height of Weir Width of Keys and Apron Solid

Abstract

To find out mechanism scour downstream weirs and study effect changing ratio width of keys Wi/Wo , length of Apron solid and studying effect of changing the lateral length B on depth and length of the maximum scour by passing different discharge and using homogeneous soil. A laboratory study was conducted to measure depth of scour downstream piano key weir type C and to show effect height weir, ratio width of keys and length of apron solid. Three heights of weir (25,30,35) cm , three ratios of width keys (1,1.25,1.5) and two distances were used For apron solid (90,120) by passing four different discharges (15, 22, 29, 36)) l/s in experiments, where number of models used nine models, on which (72) experiments were conducted. The depth of scour for all experiments that by reducing height weir , maintaining ratio width of the keys and discharge, scour decreases for all experiments. The results also showed that by increasing length of apron solid by 33.33%, the scour depth will be decreased by a rate ranging between (2.17-28.75)%. and that by increasing the percentage of the width keys from ratio (1) ) to ratio (1.5) scour depth decreases by a rate ranging between (13.04-47.38%) for all experiments, decreasing height of weirs from 35 cm to 25 cm, the percentage decrease scour depth ranged (20-40.2)%. To arrive at a positional equation in terms of variables and a coefficient of determination of R2 = 0.958 .