This document discusses energy dissipators, which are structures that reduce the kinetic energy of water flowing over spillways to prevent erosion. It describes two main types of energy dissipators - stilling basins and bucket dissipators. Stilling basins use either horizontal or sloping concrete aprons and hydraulic jumps to dissipate energy. Bucket dissipators include solid roller, slotted roller, and ski jump designs. The document explains how dissipator selection depends on the relationship between tailwater curve and flow depth. Appropriate dissipators maintain stable hydraulic jumps or direct flow into the air to safely dissipate kinetic energy for different tailwater conditions.

1. ENERGY DISSIPATORS
PRESENTED BY
KIRAN C JADHAV
GOVERNMENT COLLEGE OF ENGINEERING,
AURANGABAD
(An Autonomous Institute Of Government of Maharashtra)
DEPARTMENT OF CIVIL ENGINEERING
4/17/2017 1

2. CONTENT
• Introduction
• Types of Energy dissipators
• Stilling basins and bucket Energy dissipators
• hydraulic jump and importance
• Energy dissipation arrangement by studying
graph of discharge vs Tail Water Curve
• References
4/17/2017 2

3. DEFINITION OF ENERGY
DISSIPATORS
• The water flowing over the spillways acquires a lot of
kinetic energy by the time it reaches near the toe of
spillway ( Because of conversion of potential energy
into kinetic energy )
• To dissipate this huge kinetic energy of water and
reduce large scale of scouring the structural
arrangement is made is called as energy dissipators
4/17/2017 3

4. THE ENERGY DISSIPATORS ARE CLASSIFIED
UNDER TWO CATEGORIES
4/17/2017 4
TYPES OF ENERGY
DISSIPATORS
STILLING BASINS BUCKET TYPE

5. STILLING BASINS TYPE ENERGY
DISSIPATORS
• Definition of stilling basin :
A depression in a channel or reservoir deep enough to
reduce the velocity of the flow
• STILLING BASINS :
A ) Hydraulic jump type stilling basins
1. Horizontal apron type
2. Sloping apron type
4/17/2017 5

6. 4/17/2017 6
HORIZONTAL APRON TYPE SLOPING APRON TYPE
Source : NPTEL PDF

7. BUCKET TYPE ENERGY
DISSIPATORS
BUCKET TYPE :
1. Solid roller bucket
2. Slotted roller bucket
3. Ski jump (flip/trajectory) bucket
4/17/2017 7

8. 4/17/2017 8
Mahi bajaj sager dam across river mahi in rajasthan showing ski-jump
bucket energy dissipetor
Source : Website of Ministry of Water Resources, Government Of India

9. • Hydraulic jump : is the jump of water that takes
place when a super critical flow changes into a sub-
critical flow .
• In general , the kinetic energy of this super critical
flow can be dissipated into two way :
i ) By converting the super critical flow into sub
critical flow by hydraulic jump
ii ) by directing the flow of water into air and then
making it fall away from the toe of the structure
4/17/2017 9

10. 4/17/2017 10Source : NPTEL PDF

11. • TAIL WATER LEVEL : Refers to waters located
immediately downstream from a hydraulic structure,
such as a dam
If the graph is plotted between q and tail water level
there are five possibilities :
a) T.W.C. Coinciding with Y2 curve at all discharges
b) T.W.C. Lying above the Y2 curve at all discharges
c) T.W.C. Lying below the Y2 curve at all discharges
d) T.W.C. Lying above the Y2 curve at smaller
discharges and lying below the Y2 curve at large
discharges
4/17/2017 11

12. e ) T.W.C. Lying below the Y2 curve at smaller discharges and
lying above the Y2 curve at large discharges
4/17/2017 12
Source : S.K.Garg book

13. • Depending upon the relative position of T.W.C. And
y2 curve energy dissipation arrangement can be
provided below the spillway as follow ,
A ) T.W.C. Coinciding with Y2 curve at all
discharges :
• This is most ideal Condition for jump formation
• The hydraulic jump will form at the toe of the
spillway at all discharges
4/17/2017 13

14. • In such cases , a simple concrete apron of length 5
( y2- y1) is generally sufficient to provide protection
in the region of hydraulic jump
4/17/2017 14Source : S.K.Garg book

15. B) T.W.C. Lying above the Y2 curve at all discharges In this
case when y2 is always below the tail water,
• The jump forming at toe will be drowned out by tail water ,
and little energy will dissipated
• By constructing a sloping apron above the river bed
4/17/2017 15
Source : S.K.Garg book

16. c) T.W.C. Lying below the Y2 curve at all discharges
• if the tail water is very low, the water may shoot up out the
bucket, and fall harmlessly into the river at some, distance
downstream of the bucket in such cases ski jump bucket
energy dissipater is use
4/17/2017 16
Source : S.K.Garg book

17. 4/17/2017 17
River chenab showing the energy being dissipated by ski-jump bucket type

18. D) T.W.C. Lying above the Y2 curve at smaller
discharges and lying below the Y2 curve at large
discharges :
In this case , at low discharges the jump will be drowned and at
high discharges tail water level is insufficient in such cases
sloping apron partly above and partly below the river bed
is provided
4/17/2017 18
Source : S.K.Garg book

19. References
• Garg, S.K. "Irrigation Engineering and Hydraulic
Structures", Khanna Publishers, Delhi.
• IIT kharagpur Module of Hydraulic Structures for
Flow Diversion and Storage The National Programme
on Technology Enhanced Learning (NPTEL)
4/17/2017 19

20. Thank You
4/17/2017 20