Modelling Equation of Contraction Coefficient (Cc) and Discharge Coefficient (Cd) for Flow under Sluice Gate Using Cubic Baffle Block and Sill

One of devices in hydraulic structures that used for flow control was sluice gate. Flow under sluice gate in variation of open gate (a = 1,2,3,4 cm) and variation of discharge (Q) rise the contraction coefficient (Cc) and discharge coefficient (Cd). Fiberglass prototype model as horizontal channel was used for this experimental research with dimension: length (L) = 9 m, width (B) = 50 cm and using sluice gate installed on it, height (h) = 80 cm, thick (t) = 1 cm, width (b) = 50 cm. Two models of baffle block as cubic using end sill (code K1, 16 running, no sill, s1 = 2 cm; code K2, 16 running, s1 = 2 cm, s2 = 2.7 cm) with different dimension (Bb1 = 0.7 cm, Bb2 = 1.4 cm) installed as three row, specified location 25 cm after sluice gate. During each running test with variation open gate and discharge, the velocity (v) and height of flow (h) were measured then Froude number, contraction coefficient (Cc) and discharge coefficient (Cd) were analyzed. The result showed that cubic baffle block model K2 (used sill 2 cm and 2.7 cm, Fr = 0.09 0.88) gives the better performance modelling of Cc and Cd in term of the initial Froude number with R = 0.9152 (Cc) and R = 0.9053 (Cd). It was concluded that using three rows configuration of cubic baffle block with K2 model (1.4 cm x 1.4 cm x 1.4 cm) gave better model than K1. Keyword: Cubic Baffle Block, Sill, Froude number, Contraction Coefficient, Discharge Coefficient