Abstract

Stilling basins with dentiated or continuous sills are frequently used as energy dissipaters downstream of hydraulic structures. In this study, experiments are conducted to evaluate effects of a single vertical continuous sill and its position on control of depth and length of a forced jump in stilling basin without considering tailwater depth which is variable and totally controlled by downstream river conditions. A sill with five different heights was placed at three different longitudinal distances along a scaled model of a stilling basin. The hydraulic characteristics of the jump were measured and compared with the classical hydraulic jump under variable discharges. Results of experiments confirmed significant effect of the sill on dissipation of energy. A new relationship was developed between sill height and position, sequent depth ratio, and length of stilling basin. The advantage of the proposed relationship in practice is its capability to design stilling basin where tailwater depth is unpredictable

Key words: Hydraulic jump, baffle block, sequent depth.