Investigation of coefficient of discharge and energy loss in a semi cylindrical weir and semi cylindrical weir- gate

The present research Investigated discharge coefficient and energy loss flows of semi cylindrical wire- gate are observed. The experiments were conducted in rectangular flume with the length of 8m, width of 0.282m and height of 0.3m. in faculty of soil conservation and watershed management research institute laboratory, using physical models with diameters 70, 120 and 160 mm in height of the opening between zero until radius and differently discharging. The ratio of cylindrical structure diameter to channel width (D/B) was included range of 0.25 to 0.57 and the Froude number was conducted range of 0.012 to 0.55. The research findings have shown that in all angles alignment structure discharge coefficient and dimensionless parameter Hf/H (the ratio of energy loss to the water depth upstream) cases curvature of the upstream and curvature of the downstream respectively with increasing dimensionless parameter H/P increases and decreases. constant a (H / P), discharge coefficient and dimensionless parameter Hf / H when the curvature is upstream semi cylindrical wire-gate due to the gradual shrinkage of flow lines and thus decrease the input is less than the curvature is downstream structure.