Experimental Investigation of Hydraulic Jump Characteristics in Ogee Spillway Stilling Basin by Perforated Stepped Sill

Stilling basin as an efficiently hydraulic structure to dissipate the kinetic energy of supercritical flow generated at the downstream of a spillway and in some cases to get an economic design use baffle blocks, end sill is used in stilling basin. For control of and reducing the length of hydraulic jump, build a short sill in a stilling basin as a continuous sill can be effective. The present study focuses on the effects of a perforated stepped sill on the characteristics of hydraulic jump in ogee spillway stilling basin was. Experiments were performed for four ratios of opening of holes equal to 12, 25, 50 and 70% at three relative distance equal to10.4, 14.6 and 18.75. The results showed that using Perforated stepped sill in a stilling basin has a positive effect on control and would fix the position of hydraulic jump in a stilling basin, and that the sill with ratio of opening equal to 25% at relative distance equal to10.4 showed a maximum effect on reduction of the length of hydraulic jump compared to other sills and length of hydraulic jump reduction of 40.8% on an average in case of classical hydraulic jump. Also the best position for the sill with ratio of opening equal to 12%, based on reduction of the length of hydraulic jump is the relative distance more than 14.6.also decrease the ratio of opening and the relative distance have a positive effect on the relative energy dissipation, so that the sill with ratio of opening equal to 12% at relative distance of equal to10.4, increased the relative energy dissipation of 11% on an average as compared to the classical hydraulic jump.