Experimental Investigation of Discharge Characteristics of an Adjustable Cylindrical Weir–Gate under Weir-Only, Gate-Only, and Combined Flow Conditions

This experimental study investigates the discharge coefficient (Cd) of an adjustable cylindrical weir-gate under weir-only, gate-only, and combined weir-gate flow conditions. Four cylinder diameters (D = ۱۱۰, ۱۲۵, ۱۶۰, and ۲۰۰) mm and seven gate openings (a = ۰, ۱۰, ۲۰, ۳۰, ۴۰, ۵۰, and ۶۰) mm were tested over a discharge range of (Q = ۳۴)–۸۶ l/s, resulting in ۱۱۲ experimental runs. The effects of upstream Froude number (Frup), downstream Froude number (Frdown), upstream depth ratio (yup/D), downstream depth ratio (ydown/D), head ratio over the cylinder (Hw/D), and head-to-opening ratio (Hw/a) on (Cd) were investigated. Under weir-only flow conditions, (Cd) generally increased with increasing (Frup) and (Hw/D). Under gate-only and combined weir-gate flow conditions, the hydraulic response depended on both cylinder diameter and gate opening. Smaller gate openings increased the upstream water level and promoted the transition from gate-only to combined weir-gate flow, whereas larger openings increased the contribution of underflow. The ratios (Hw/D) and (Hw/a) clearly reflected the transition between the two flow regimes and the increasing contribution of overflow. Cylinder diameter also influenced (Cd), although no single diameter showed superior hydraulic performance under all tested conditions. The results demonstrate that the discharge coefficient of an adjustable cylindrical weir-gate is governed by the interaction among cylinder diameter, gate opening, discharge, and upstream head

کلیدواژه ها:

Cylindrical weir– gate ، Combined flow ، Discharge coefficient ، Free overflow ، Gate underflow ، Hydraulic control