energy dissipator in hydraulic structure

types of energy dissipator in hydraulic structure

1. ENERGY DISSIPATORS PRESENTED BY KIRAN C JADHAV GOVERNMENT COLLEGE OF ENGINEERING, AURANGABAD (An Autonomous Institute Of Government of Maharashtra) DEPARTMENT OF CIVIL ENGINEERING 4/18/2017 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 4/18/2017 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 4/18/2017 3

4. THE ENERGY DISSIPATORS ARE CLASSIFIED UNDER TWO CATEGORIES 4/18/2017 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 4/18/2017 5

6. 4/18/2017 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 4/18/2017 7

8. 4/18/2017 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 4/18/2017 9

10. 4/18/2017 10 Source : 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 : T.W.C. Coinciding with Y 2 curve at all discharges T.W.C. Lying above the Y 2 curve at all discharges T.W.C. Lying below the Y 2 curve at all discharges T.W.C. Lying above the Y 2 curve at smaller discharges and lying below the Y 2 curve at large discharges 4/18/2017 11

12. e ) T.W.C. Lying below the Y 2 curve at smaller discharges and lying above the Y 2 curve at large discharges 4/18/2017 12 Source : S.K.Garg book

13. Depending upon the relative position of T.W.C. And y 2 curve energy dissipation arrangement can be provided below the spillway as follow , A ) T.W.C. Coinciding with Y 2 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 4/18/2017 13

14. In such cases , a simple concrete apron of length 5 ( y 2 - y 1 ) is generally sufficient to provide protection in the region of hydraulic jump 4/18/2017 14 Source : S.K.Garg book

15. B) T.W.C. Lying above the Y 2 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 4/18/2017 15 Source : S.K.Garg book

16. c) T.W.C. Lying below the Y 2 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 4/18/2017 16 Source : S.K.Garg book

17. 4/18/2017 17 River chenab showing the energy being dissipated by ski-jump bucket type

18. D) T.W.C. Lying above the Y 2 curve at smaller discharges and lying below the Y 2 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 4/18/2017 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) 4/18/2017 19

20. Thank You 4/18/2017 20