Author(s): Krishna Kumar Durgam; Ali Shariq; Zulfequar Ahmad

Linked Author(s):

Keywords: Energy dissipators; Hydraulic jump type; Baffled spillway type; Vertical drop type; Scour; Water surface profile

Abstract: Energy dissipators are essential not only to prevent scouring downstream from a hydraulic structure but also to protect the structure and its appurtenances. This research is to examine the efficiency of different types of energy dissipators provided downstream of a spillway. Three types of energy dissipators i.e. hydraulic jump, impact (baffled apron) and vertical drop dissipators were designed and tested to arrive at best of them, for different discharges through sectional physical modelling of two bays of the aqueduct (one full bay and two half bays separated by two piers) on a scale of 1:25. Depth of flow, velocity, and scour on downstream were measured at the centrelines of the bay and pier at different points along the aqueduct. The maximum scour measured for hydraulic jump, baffled apron spillway, and vertical drop type dissipators at the centreline of the bay was 1.6 m, 2.6 m, and 2.1 m respectively for the highest discharge. Scour was further increased to 2.0 m, 4.3 m, and 2.7 m respectively with retrogression of the bed by 1.0 m which indicates that the scour depth was increased significantly by about 25% with retrogression by 1.0 m as compared to without retrogression. The minimum scour indicates higher dissipation of energy there by efficiency of the energy dissipator. It was found that hydraulic jump type dissipator is more efficient as compared to the other two, as it resulted in minimum scour and vertical drop type dissipator is more efficient for the lower discharges.

DOI: https://doi.org/10.3929/ethz-b-000675921

Year: 2024