Controlled Ski-jump Spillway Model Design According to IS code

Ogee spillways are used to monitor reservoir releases. Ogee spillway is a weir with an ogee (S-shaped) overflow profile. A curve solid surface provided at the toe of the spillway is known as a ski-jump bucket. Ski-jump bucket type energy dissipator is considered more suitable when tail water depth is much lower than the sequent depth of a hydraulic jump. In the ski-jump bucket, the flow coming down the spillway is thrown away in air from the toe to a considerable distance as a free discharging upturned jet (trajectory), which falls on the channel bed downstream. In the ski-jump bucket, only part of the energy is dissipated through interaction of the jet with the surrounding air. The remaining energy is accorded to the channel bed below. This paper describes the design of a Controlled ski -jump spillway model with guidelines in accordance with the IS Code.

Simulation and Analytical Estimation of Spillway Flip Bucket Parameters

Spillway is an important component of the storage structure, meant to discharge excess amount of water in the reservoir. It also acts as a measure to control floods and protect the structure from overtopping and failure. For the safety of the structure, an appropriate energy dissipator is provided at the toe of the spillway. Of many alternatives, a flip buclet is often provided as a energy dissipater and its design plays a significant role. The design involves an accurate estimation of various parameters viz., trajectory jet velocity, angle of throw, length and height of the trajectory jet. The present study was carried out to analytically estimate the design parameters and compare them with the ANSYS-CFD simulation results. A new equation is proposed by means of user-defined function, based on the macro generated VOF - multiphase analysis. The analytical results estimated by the proposed equations were observed to have a good consonance with the simulation results having a variation less than 5%

Pressure distribution and cavitation in counter-vortex flow energy dissipators of hydraulic spillways

The article is devoted to the study of cavitation phenomena of counter-vortex flow energy dissipators that can be used in hydraulic spillways. The spillways providing the surface flow transitionn at hydraulic structures are equipped with energy dissipators of the discharged flow. An increase in the effective pressure on the hydropower project leads to an increase in the flow velocities and, hence , to an increase in the loads acting on the structures. One of such a manifestation is cavitation and cavitation erosion associated with it, which can lead to destruction of structures. The objective of the study consists in determining the cavitation characteristics of counter-vortex flow energy dissipators. The study was carried out by modeling using high-head physical models. The counter-vortex method of excess flow energy dissipation based on the work of viscous friction forces allows the flow energy to be dissipated in a very short part of the flow conductor system of the spillway. This feature of the counter-vortex flow energy dissipator imposes special requirements to the study of cavitation phenomena. The carried out studies resulted in obtaining the distribution of pressures lengthwise the flow conductor system of the energy dissipator with spiral swirls. The values of the cavitation coefficient and relative pressure at different points of the device are given. In the conclusions it is noted that the most dangerous part from the viewpoint of cavitation orrurence is the initial section of the flow energy dissipation chamber; cavitation due to flow separation and bubble cavitation occur within the flow and does not affect the structural elements; on a large-scale model working for 500 hours at pressures of up to 70 m cavitation erosion of the walls has not been detectd.