Hydraulics Lesson 9

7/30/2019 Hydraulics Lesson 9

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HYDRAULICS

g.Dep.-Hydraulic

A.SUNA ERSESAssist.Prof.Dr.

[email protected]

EnvironmentalE

.(Tel: 0 264 295 5465)

Sakarya University, Engineering Faculty, Environmental

Engineering Department, Esentepe Campus,

54187 SAKARYA

sUnderstand how flow in open channels differs from flow in

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ydraulic

EnvironmentalE LESSON 9: OPEN CHANNEL


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Open channel flow is the flow of a liquid in a conduit with a free surface.

SSY

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Pipe Free Surface Open Channel

EnvironmentalE the flow of water in creeks, streams, rivers, and floods, as well as the draining

of rainwater off highways, parking lots, and roofs

Human-made open-channel flow systems

irrigation systems, sewer lines, drainage ditches, and gutters, and the design

of such systems is an important application area of engineering.

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Classification of Open Channel Flow

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Variation of flow parameters with time

Variation of flow parameters with space

Based on turbulenceBased on concept of critical flow

Based on conceptualizing the flow as 1D, 2D or 3D

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Re = Rh.V /

Re =500 olur

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Open channel:Re


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Froude No (Fr)= V/(gy)1/2

Where

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Fr = 1 for critical flow

g=the gravitational acceleration

V=average liquid velocity at a cross section

y=flow depth

EnvironmentalE Fr < 1 for subcritical flow

Fr > 1 for supercritical flow

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s EXAMPLE 1 Water at 20C is flowin uniforml in a wide rectan ular

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channel at an average velocity of 2 m/s. If the water depth is 0.2 m,

determine (a) whether the flow is laminaror turbulent and (b) whetherthe flow is subcritical orsupercritical

20C are = 998.0 kg/m3 and = 1.00210-3 kg/m s

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s EXAMPLE 2 Water at 10C flows in a 3-m-diameter circular

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channel half-full at an average velocity of 2.5 m/s. Determine

the hydraulic radius, the Reynolds number, and the flowregime (laminar or turbulent).

10C are = 999.7 kg/m3 and = 1.30710-3 kg/m s

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http://landscape.ced.berkeley.edu/~kondolf/courses/LA222/lecture%2010-

open%20channel%20flow.pdf

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Hydraulics Lesson 9

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