Hydraulic jump explanation


hydraulic jump

A hydraulic jump is a phenomenon in the science of hydraulics that is frequently observed in open channel flow such as rivers and spillways. When liquid at high velocity discharges into a zone of lower velocity, a rather abrupt rise occurs in the liquid surface.


What causes a hydraulic jump?
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.
How do you calculate hydraulic jump?
How do you calculate hydraulic jump?
Equations for Hydraulic Jump Calculations

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.







 



What is tail water depth in hydraulic jump?
10. 2. Based on Tail water depth • The depth downstream of a hydraulic structure is called tailwater depth. yt = tailwater depth, ya = Depth at the vena-contracta, y2 = sequent depth to ya 1) Free jump: The jump with yt equal to or less than y2 is called free jump.
How is Froude number calculated?
It is generally expressed as Fr = v/(gd)1/2, in which d is depth of flow, g is the gravitational acceleration (equal to the specific weight of the water divided by its density, in fluid mechanics), v is the celerity of a small surface (or gravity) wave, and Fr is the Froude number.
Why is hydraulic jump important?
Energy dissipation by a hydraulic jump

One of the most important engineering applications of the hydraulic jump is to dissipate energy in channels, dam spillways, and similar structures so that the excess kinetic energy does not damage these structures.
















dissipate energy in channels, dam spillways, and similar structures so that the excess kinetic energy does not damage these structures.






 

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