Hydraulic Jump

Flow in super critical state is an unstable type of flow. It has a tendency to transfer n to sub critical flow. Flow depth is small in a supercritical state. which increases suddenly while changing the subcritical state. This phenomenon sudden increase in depth of flow is called a HYDRAULIC JUMP.

1. Water And Waste Water Engineering Hydraulic Jump

2. Hydraulic Jump Flow in super critical state is an unstable type of flow. It has a tendency to transfer n to sub critical flow. Flow depth is small in super critical state.which increase suddenly while changing sub critical state. This phenomenon sudden increase in depth of flow is called as HYDRAULIC JUMP. Hydraulic jump occurs when a steam moving with super critical velocity meets a steam having large depth with sub critical velocity.

3. Hydraulic jump occur frequently in A channel below a regulating sluice At the foot of spillway at the place where a steep channel bottom slope suddenly changes to a flat slope.

4. Classification of jump Jump are classified in to five categories Under jump: The water surface shows undulation with small ripple on the surface. Weak jump: in this case series of small rollers form on jump surface. only a small amount of energy is dissipated. Oscillating jump: In this jump, flow oscillates in a random manner between the bed of channel to water surface. Steady jump : It is well stabilized jump. Roller are fully developed to cause sufficient energy loss. Strong jump: Water surface is rough. It dissipates max. energy.

5. C l ass ifi c a ti on of h ydr a uli c jump s : ( a ) ( b ) ( c ) ( d ) ( e ) F r =1. t o 1.7 : un d ul a r jump s ; F r =1. 7 t o 2.5 : w e a k jump ; F r =2. 5 t o 4.5 : o s c ill a tin g jump ; F r =4. 5 t o 9.0 : s t e a dy jump ; F r =9.0 : s t r o n g jum p .

6. Use of hydraulic jump Hydraulic jump is used to dissipate or destroy the energy of water where it is not needed otherwise it may cause damage to hydraulic structures. It may be used for mixing of certain chemicals like in case of water treatment plants. It may also be used as a discharge measuring device.

7. Energy dissipation Hydraulic jumps are one of the most effective options in dissipating energy over water structure Turbulent flow and secondary waves cause most of the energy dissipation Applying the conservation of momentum equation, the energy loss can be calculated Δ E = (y ₂ - y ₁ )³ / (4y ₁ y ₂ ) y ₁ = Flow depth at supercritical flow y ₂ = Flow depth at subcritical flow

8. Energy loss diagram The diagram above illustrates a hydraulic jump and the energy loss from E1 to E2. The supercritical depth (y1) jumps to a larger depth, subcritical depth (y2), as the velocity decreases from V1 to V2.

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