Contraction coefficient (cc) characteristic for flow under sluice gate using trapezoid baffle block and sill

Laboratory experiment was development to know contraction coefficient (Cc) characteristic for the flow under sluice gate while it operated with variation discharge and open gate using trapezoid baffle block with sill. Prototype model as horizontal channel used sluice gate installed on it made from fiberglass. Dimension of horizontal fiberglass channel: length (L) = 9 m, width (B) = 50 cm; sluice gate dimension, height (h) = 80 cm, thick (t) = 1 cm, width (b) = 50 cm. Variation of discharge (Q) and open gate (a = 1,2,3,4 cm) make the flow rise the contraction coefficient (Cc). Models of baffle block as trapezoid (Bb = 2.8 cm) installed as three row, specified location 25 cm after sluice gate using end sill (code T4-A, 10 running; code T4-B, 10 running; T4-C, 10 running; T4-D, 10 running). The height of flow (h) and velocity (v) were measured during each running test then Froude number and contraction coefficient (Cc) were analyzed. The result showed that trapezoid baffle block model T4-A (28 cm × 28 cm × 28 cm) (Fr = 0.12 - 0.50) gives the better performance modelling of Cc in term of the initial Froude number with R² = 0.9186, L_s1, L_s2 = 32 mm, L₂ = 100 cm. It was concluded that using three rows configuration of trapezoid baffle block with T4-A model gave better model than T4-B, T4-C, T4-D.