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Published bySabrina Major Modified over 2 years ago

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Change of the flow state Hydraulic Drop: A rapid change in the depth of flow from high stage to a low stage will result in a steep depression in the water surface. Such a phenomenon is generally caused by a abrupt change in the channel slope or cross section. Free overfall: is a special case of the hydraulic drop. It occurs where the bottom of a flat channel is discontinued. Hydraulic Jump: when the rapid change in the depth of flow is from a low stage to a high stage the result is usually an abrupt rise of water surface. It occurs frequently in a canal below a regulating sluice, at the foot of a spillway, or at the place where a steep channel slope suddenly turns flat.

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Hydraulic drop Example

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Hydraulic Jump Hydraulic jump is formed in a channel whenever supercritical flow changes to subcritical flow Jump location, sharp discontinuity in the water surface and considerable amount of energy is dissipated due to turbulence y1 and y2 are called sequent depths (Chaudhry, 2008)

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Hydraulic Jump (Chaudhry, 2008)

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Example on Hydraulic Jump The discharge in a 20-m wide, rectangular, horizontal channel is 80 m 3 /s at a flow depth of 0.5 m upstream of a hydraulic jump. Determine the flow depth downstream of the jump and the head losses in the jump.

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Example solution

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Hydraulic Jump at a Sluice Gate Outlet (Chaudhry, 2008)

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Hydraulic Jump at a Sluice Gate Outlet Example A hydraulic jump is formed just downstream of a sluice gate located at the entrance of a channel. There is a constant-level lake upstream of the sluice gate. The flow depth and velocity in the channel downstream of the jump are 5.2 ft and 4.3 ft/sec, respectively. Determine the water level in the lake. Assume the losses for flow through the gate are negligible. Assume rectangular cross section and horizontal channel bed.

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Solution

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Force on a Sluice Gate Example A sluice gate is used to control the water flow rate over a dam. The gate is 20 ft wide, and the depth of the water above the bottom of the sluice gate is 16 ft. The depth of the water upstream of the gate is 20 ft, and the depth downstream is 3 ft. Estimate the flow rate under the gate and the force on the gate. The water density is 62.4 lbm/ft 3

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Force on a sluice gate Example

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