Hydraulic Energy Dissipators - A Review
Hydraulic Energy dissipators are devices to protect downstream areas of basin from erosion by reducing the velocity of flow up to an acceptable limit. The stilling basins are transition structures fabricated to dissipate excess energy confined by flow with high velocity at the outlet of conduit or tunnel so that the flow beyond the basin does not threaten the firmness of bed and banks of downstream channel in structures like culvert spillways, canal, etc. from scouring. Henceforth proper attention needed by hydraulic engineers for t he design of energy dissipators so as to obtain optimum energy dissipation at outlet. The type of stilling basin most suitable at a particular location mainly depends upon initial velocity of flow and initial Froude Number. This paper describe about the different type of energy dessipators with different appurtanances used in hydraulic structures for protection work.
GEOMETRY EFFECT ON FLOW AND SEDIMENT DEPOSITION PATTERNS IN SHALLOW BASINS
The design of stilling basin geometry of flood mitigation dams in view of clear water flow may differ when considering of the water-sediment and deposition effects. To ensure effectiveness of energy dissipation, appropriate design of stilling basin leading to optimal geometry is required. The present study investigates the influence of the shallow basin geometry on flow and sediment deposition patterns. The effect of the geometry was investigated using systematic physical experiments, numerical simulation, and field data. This allowed to identify the optimal stilling basin shape of the flood mitigation dam that dissipates more energy, minimizes the deposition and reduces the number of horizontal recirculation cells. The results help to understand the influence of geometry on the flow stability, sediment deposition and flushing process in order to choose the appropriate stilling basin geometry. The prediction of sediment profile depends on the prediction of flow pattern and, in turn, sediment deposits were able to change the flow structure.
Hydraulic Jump within Gradually Expanding Channel
This expanding channel jump is considered to behave as a section of a circular jump. Equations describing the characteristics of the expanding channel jump are derived. The observations were conducted using six different angles of divergence. The experimental results showed a close agreement with the theoretical solutions. The general equation developed for the jump, with proper evaluation of the side pressure force effect, describes the phenomenon regardless of the angle of divergence. An empirical expression for approximating the location of the jump within the transition was also developed.