See Fig. 14.85. But due to losses the specific energy head after the jump is E 2 and the actual depth after the jump is d 2 = E 2 Q’. In the figure E 1 E 2 = loss of head h l due to hydraulic jump.
Is mechanical energy lost in a hydraulic jump?
A hydraulic jump is an abrupt change from a shallow high-speed flow to a deep low-speed flow of lower energy. ... Across a hydraulic jump: – mass is conserved; – the momentum principle is satisfied; – mechanical energy is lost (mostly as heat) .
How do you calculate hydraulic jump?
y2/y1 = (1/2)[-1 + (1 + 8Fr12)1/2] ; V1 = Q/(by1) ; and Fr1 = V1/(y1g)1/2. The upstream velocity, V1 and upstream Froude number, Fr1, need to be calculated first, using the last two equations, then the downstream depth of flow, y2 can be calculated using the first equation.
Why are hydraulic jumps effective for energy dissipation?
Because a hydraulic jump causes so much turbulence , it is able to effectively dissipate hydraulic energy as heat. So many energy dissipators, also called stilling basins, are designed to force a hydraulic jump to occur.
What is the energy loss in hydraulic jump?
Although momentum is conserved throughout the hydraulic jump, the energy is not. There is an initial loss of energy when the flow jumps from supercritical to subcritical depths. The resulting loss of energy is equal to the change in specific energy across the jump and is given by the equation for ΔE below.
Why do hydraulic jumps occur?
A hydraulic jump is a phenomenon that occurs in fast-moving open flows when the flow becomes unstable . When a jump occurs, the height of the liquid surface increases abruptly resulting in an increased depth and decreased average flow velocity downstream.
What do you mean by hydraulic jump?
Hydraulic jump, Sudden change in water level , analogous to a shock wave, commonly seen below weirs and sluice gates where a smooth stream of water suddenly rises at a foaming front. The fact that the speed of water waves varies with wavelength and with amplitude leads to a wide variety of effects.
In which case is a hydraulic jump not possible?
Explanation: Hydraulic jump is not possible when the initial speed is less than the critical speed . There is a transition that is created during the change. Fluid flow after the hydraulic jump is typically rough and choppy turbulent flow.
What causes the hydraulic jump to occur in the horizontal channel?
A hydraulic jump occurs when the upstream flow is supercritical (F>1) . To have a jump, there must be a flow impediment downstream. The downstream impediment could be a weir, a bridge abutment, a dam, or simply channel friction. Water depth increases during a hydraulic jump and energy is dissipated as turbulence.
Is a hydraulic jump a flow control?
Controlling the flow of water is one of the fundamental objectives of modern infrastructure, from flooding rivers to irrigation canals, stormwater drainage facilities to aqueducts, and even the spillways of dams.
Where are hydraulic jumps used?
Hydraulic jump usually maintains the high water level on the down stream side . This high water level can be used for irrigation purposes. Hydraulic jump can be used to remove the air from water supply and sewage lines to prevent the air locking.
What are the effects of hydraulic jump?
Actually the hydraulic jump usually acts as the energy dissipator
How does a hydraulic jump behave like a shockwave?
A hydraulic jump is a fluid shockwave created at the transition between laminar and turbulent flow . ... Friction against the sink surface slows the flow until an abrupt change occurs. At this point, the depth increases as water piles up in the transition region and flow becomes turbulent [1].
