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    Design of Chute and Syphone Spillway

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    Benson Nkya
    This document discusses the design of chute and siphon spillways. It describes how a chute spillway consists of an open channel called a chute that carries water over the spillway crest to downstream. An entrance channel is needed to convey water to the control structure. Side walls must be tall enough to prevent overflow. The chute profile should conform to site conditions with uniform or curved slopes. A siphon spillway operates using siphonic action, with two main types being hood or saddle and volute siphon. Hydraulic considerations for both include discharging capacity, priming depth, flow regulation, and cavitation effects.

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    Design of Chute and Syphone Spillway

    Uploaded by

    Benson Nkya
    13 views17 pages
    This document discusses the design of chute and siphon spillways. It describes how a chute spillway consists of an open channel called a chute that carries water over the spillway crest to downstream. An entrance channel is needed to convey water to the control structure. Side walls must be tall enough to prevent overflow. The chute profile should conform to site conditions with uniform or curved slopes. A siphon spillway operates using siphonic action, with two main types being hood or saddle and volute siphon. Hydraulic considerations for both include discharging capacity, priming depth, flow regulation, and cavitation effects.

    Original Description:

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    Original Title

    Design of chute and syphone spillway

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    This document discusses the design of chute and siphon spillways. It describes how a chute spillway consists of an open channel called a chute that carries water over the spillway crest to downstream. An entrance channel is needed to convey water to the control structure. Side walls must be tall enough to prevent overflow. The chute profile should conform to site conditions with uniform or curved slopes. A siphon spillway operates using siphonic action, with two main types being hood or saddle and volute siphon. Hydraulic considerations for both include discharging capacity, priming depth, flow regulation, and cavitation effects.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    13 views17 pages

    Design of Chute and Syphone Spillway

    Uploaded by

    Benson Nkya
    This document discusses the design of chute and siphon spillways. It describes how a chute spillway consists of an open channel called a chute that carries water over the spillway crest to downstream. An entrance channel is needed to convey water to the control structure. Side walls must be tall enough to prevent overflow. The chute profile should conform to site conditions with uniform or curved slopes. A siphon spillway operates using siphonic action, with two main types being hood or saddle and volute siphon. Hydraulic considerations for both include discharging capacity, priming depth, flow regulation, and cavitation effects.

    Copyright:

    © All Rights Reserved
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    of 17

    Design Chute and Siphon Spillway

    Chute Spillway

    • A chute spillway consists of a


    steep sloped open channel
    called a chute or trough, which
    carries the water passing over the
    crest of spillway to the river
    downstream
    Entrance Channel
    • An approach channel is required to draw water from the reservoir and
    convey it to the control structure.
    • The friction head lost in the entrance channel upto the spillway crest
    can be calculated by:
    Hf= Sf*L= (n2 V2L)/(R4/3)

    Where n=manning coefficient of roughness


    v=velocity in channel
    R= hydraulic mean depth
    L= length of channel
    Sf = mean energy slope b/w two point
    Side Wall of Chute
    • The side wall of chute should be of such height that water doesnot
    spill over them
    • A sufficient freeboard must be provided
    FB= 0.61+0.04Vm . (dm )1/3
    Where Vm= mean velocity of water in the chute
    dm= mean depth of water in the chute
    Chute Channel
    • The profile of discharge channel should usually be selected to confirm
    to topographic and geological site conditions and should be provided
    with uniform slope in reaches joined by vertical curves

    • When slope of chute changes from steeper to mild a concave vertical


    curves shall provided. The radius should be less than 10d, where d id
    depth of water

    • When slope of chute changes from mild to steeper a convex vertical


    curves shall provided.
    • The curvature should be parabolic in shape given by:
    q= -xtanø- (x2/(k(4(d+hv ) cos2ø))
    Where ø= slope angle of the floor upstream
    (d+hv )=specific energy of flow at junction point
    K= constant which is ≥ 1.5
    Siphon Spillway
    • A siphon spillways operates on the principle of siphonic action.
    • There are basically two types of siphon spillways
    • Hood or Saddle siphon (as shown in Figure 1)
    • Volute siphon(as shown in Figure 2)
    • All necessary precautions must be taken to ensure that the vacuum is
    maintained and that it does not become so excessive as to cause
    cavitation
    • The maximum negative pressure at the spillway crest is theoretically
    10 m of water at sea level
    • Allowing for the vapor pressure of water, loss due to turbulence, etc.,
    the maximum net effective head is rarely more than about 7.5 m

    • Which means that the initial velocity in any siphon cannot exceed
    about 12 m/s at the inlet
    Hydraulic Design Consideration

    Discharging capacity
    Priming depth
    Regulating flow
    Effect of waves in the reservoir
    Cavitation Vibration
    Discharging Capacity
    • The flow in the throat section of a saddle siphon can be idealised as a
    free vortex, so that
    This velocity should be the same at all sections along the siphon
    barrel unless there is expansion or contraction of the section
    • when the siphon is running full, the velocity is given by the total head H

    • Total head H (from reservoir level up to the tail water level)


    Cont…..

    Energy Equation (Enterance and Exit)

    The required outlet area Ao can then be calculated from Vo


    THANK YOU

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