Energy Dissipation By Using Different Sizes And Configurations Of Direction Diverting Blocks On Spillways

Abstract

This study aims to investigate the effects of applying the direction diverting blocks, (DDBs),fixed on an ogee spillway surface with different slope on energy dissipation. Three ogee spillway models were prepared with slope of 1:1, 0.85:1, and 0.75:1. All models were constructed with a scale ratio of 50:1. Six sizes of DDBs of triangular shapes were used. These blocks were arranged in eighteen configurations for slope 1:1, fourteen configurations for each spillway models with slope 0.85:1 and 0.75:1. The configurations differ in spacing between rows of blocks and the number of rows. Eight hundred and forty six test runs were carried out to investigate the energy dissipation downstream the three spillway models with and without using DDBs in different configurations. Froude Number and the distance of the hydraulic jump, measured from the toe of the weir, were used as a measure of flow energy and to provide a base for comparisons.When DDBs were used, the maximum reduction in Froude Number was 36%, 89%, and 93% for spillway models with slopes 1:1, 0.85:1, and 0.75:1, respectively. A full reduction in the values of hydraulic jump distance was achieved in the three spillway models. The DDBs were efficient in reducing the distance of the hydraulic jump, and as a result, if the DDBs are used, then the stilling basin will be much shorter or may be eliminated.