Influence of baffle block and sill for determination characteristic of contraction coefficient (cc) and discharge coefficient (cd) for flow under sluice gate

Abstract

The contraction coefficient (Cc) and discharge coefficient (Cd) always rise in flow while sluice gate operated with variation of open gate and discharge (Q). To know it, laboratory experiment was development used trapezoid baffle block compared with sill. This experimental research used prototype model made from fiberglass (horizontal channel), sluice gate installed on it. 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). Two models of trapezoid baffle block (T1, T2) installed as three rows, specified location 25 cm after sluice gate combine with sill (different dimension). Water depth (h) and velocity (v) were measured during each running test then Froude number, contraction coefficient (Cc) and discharge coefficient (Cd) were calculated. The result showed that trapezoid baffle block model T2 (used no sill, sill 2 cm and sill 2.7 cm, Fr = 0.11 - 0.75) gives the better performance modelling of Cc and Cd in term of the initial Froude number with R 2 = 0.8086 (Cc) and R 2 = 0.8273 (Cd). It was concluded that using three rows configuration of trapezoid baffle block, T2 model gave better model than T1.