Hydraulic jump location control

CONTROLLING THE LOCATION OF
HYDRAULIC JUMP IN RECTANGULAR
CHANNEL
SUBMITTED BY SUBMITTED TO
SIDDHARTH UPADHYAY Mr. S ANBU KUMAR
2K15/HFE/15 ASSOCIATE PROFESSOR
Department of Civil Engineering

INTRODUCTION
• Statistics and studies made by International Commission on Large
Dams (ICOLD) show that more than 20% of dam accidents occurred
due to poor provision of energy dissipation arrangements.
• Normally energy dissipators are designed for ‘design discharge’ of
spillway. But their performance is affected during varying discharge
condition.
• In majority of failure cases, the jump is not clear – i.e. jump is either
swept up or drowned.
• Our present study objective is to design a suitable design of
hydraulic jump type energy dissipator for tail water deficiency and
steady flow. This can largely reduce dependency on TWRC without
disconnecting it from JHC.
• Efforts are made to produce required JHC at all discharges to form
clear jumps.

Damaged stilling basin of sardar
sarovar dam

• Sardar Sarovar Project (SSP) is one of the major
projects in India. In the year 1999 it is reported
that during a flood in monsoon season, 10,000
m3 of concrete was washed out due to flood
flows.
• The design discharge of spillway is 87,000m3/s.
The flood was even lesser than 50% of the design
discharge.
• The approximate cost of concrete that washed
out was Rs. 3 crore

View of dislodged panel at Bhama askhed dam

Definition sketch of hydraulic jump

Design of rectangular stepped weir
(Section A-A earlier shown)

FORMULA USED FOR DETERMINATION OF DIMENSION
OF STEPPED WEIR

Classification of tail water conditions
for the design of energy dissipator

FACTORS AFFECTING HYDRAULIC
JUMP
Factors affecting hydraulic jump are
• Total head on upstream of sluice gate (H),
• Pre jump depth (y1) ,
• Post jump depth (y2),
• Crest height of weir (y'),
• Head over weir crest (h) and tail water depth (yt).
• Another non dimensional important parameter
that governs hydraulic jump phenomenon is
supercritical Froude number Fr1.

Dimensions and Data of model used in
fluent
Height of sluice gate H=0.4m,
Height of flume H’=0.45m
Width of flume B=0.3m,
Length of flume L=4m
Max discharge Qmax=0.01 m3/s,
Min discharge Qmin=0.002 m3/s,
Crest height of weir y'=0.015m

Table 1: Output of Mathematical Procedure for Data
(Horizontal apron and Cd = 0.623)
Sr. No. Q y1 y2 H Fr1 B
m3/s M M M M
1 0.0020 0.0024 0.0605 0.0455 18.3350 0.1119
2 0.0028 0.0033 0.0714 0.0564 15.4960 0.1336
3 0.0036 0.0043 0.0807 0.0657 13.6661 0.1463
4 0.0044 0.0052 0.0889 0.0739 12.3614 0.1569
5 0.005 0.0062 0.0965 0.0814 11.3709 0.1660
6 0.0060 0.0071 0.1034 0.0884 10.5857 0.1741
7 0.0068 0.0081 0.1098 0.0948 9.9435 0.1816
8 0.0076 0.0090 0.1159 0.1009 9.4056 0.1884
9 0.0084 0.0100 0.1216 0.1066 8.9466 0.1949
10 0.0092 0.010947 0.1270 0.1120 8.5487 0.2010
11 0.0100 0.011899 0.1322 0.1172 8.1997 0.2067

Hydraulic jump at discharge 0.0020 m3 /sec

Table 2: Comparisons of post jump depth of experimental and
fluent value at Cd = 0.60
Test Discharge Post jump Post jump Tail water
No. Q m3/s Depth Depth depth
y2 m y2 m yt m
(Fluent) (experimental) (Fluent) (Fluent)
1 0.0100 0.132 0.1210 0.063
2 0.0092 0.1270 0.1161 0.059
3 0.0084 0.1216 0.1089 0.056
4 0.0068 0.1098 0.1040 0.049
5 0.0050 0.0968 0.0913 0.041
6 0.0040 0.0865 0.0869 0.035
7 0.0020 0.0605 0.0621 0.028

Comparisons of post jump depth of experimental and fluent
value at Cd = 0.60
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0 0.002 0.004 0.006 0.008 0.01 0.012
y2
Discharge (m3/s)
JHC Exp.
JHC fluent

Table 3: Comparisons of post jump depth of experimental and
No. Q m3/s Depth depth Depth
y2 m y2 m yt m
(Fluent) (Experimental) (Fluent) (Fluent)
1 0.0100 0.1322 0.1140 0.0540
2 0.0092 0.1270 0.1110 0.0510
3 0.0084 0.1216 0.1035 0.0475
4 0.0068 0.1098 0.1010 0.0464
5 0.0050 0.0965 0.0850 0.0363
6 0.0040 0.0850 0.0810 0.0330
7 0.0020 0.0605 0.0587 0.0270

Comparison of Experimental and Fluent – JHC (y 2) at for
horizontal apron (Cd = 0.65)
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0 0.002 0.004 0.006 0.008 0.01 0.012
Post jump Depth y2 m (Experimental)
Post jump depth y2 m (Fluent)

Table 4 : Comparisons of post jump depth of experimental and
No. Q m3/s Depth depth Depth
y2 m y2 m yt m
(Fluent) (Experimental) (Fluent) (Fluent)
1 0.0100 0.1322 0.1228 0.044
2 0.0092 0.1270 0.1240 0.043
3 0.0084 0.1216 0.1211 0.039
4 0.0068 0.1008 0.0984 0.036
5 0.005 0.0965 0.0960 0.032
6 0.0020 0.0605 0.060 0.027

Comparisons of post jump depth of experimental and fluent
value at Cd = 0.63
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0 0.002 0.004 0.006 0.008 0.01 0.012
Post jump Depth y2 m (experimental)
Post jump depth y2 m (Fluent)

Table 5: Dimension of Pawana Dam
spillway model by Froude’s law (Scale 1 : 40)
Design Parameter Designation Prototype Model
Stilling Basin width B 12m 0.3m
Stilling Basin length L 60m 1.5m
Height of spillway H 25.3m 0.6325m
Height of crested weir h 4.36 0.109
Top width of crested
weir
b 2.95 0.074
Coefficient of discharge Cd 0.623 0.623
Crest height of weir Y’ 0.024

Table 6 : Comparison of post jump depths for Pawana dam –
experimental and Fluent (designed weir)
No. Q m3/s Depth Depth Depth
(Fluent) y2 m y2 m yt m
(Expt) (Fluent) (Expt)
1 0.0200 0.195 0.2070 0.054
2 0.0181 0.186 0.1922 0.052
3 0.0160 0.175 0.1846 0.049
4 0.0130 0.158 0.1640 0.045
5 0.0095 0.135 0.1455 0.04
6 0.0077 0.120 0.1260 0.037
7 0.0065 0.110 0.1204 0.035
8 0.0043 0.090 0.1002 0.03

Comparison of Experimental and Fluent – JHC (y 2) for Proposed
designed weir
0
0.05
0.1
0.15
0.2
0.25
0 0.005 0.01 0.015 0.02 0.025
JHC EXPERIMENTAL
JHC FLUENT

Conclusions
• The performance is checked for six discharges (20%, 50%, 68%, 84%, 92%
and 100% of the design discharge). It is found that for all these discharges
clear hydraulic jumps are formed and are located near toe of spillway.
• There was good correlation found between experimental values and fluent
values ranging between 0.9 to 0.98 .
• Among all the values of coefficient of discharge for design of weir Cd =
0.623 is found to be perfect.

Limitations
• The method developed in the study is
applicable for steady flow only.
• There are chances of cavitations in weir due to
too many rectangular sharp edges.

Unique Advantages of Proposed
Stilling Basin
1. As tail water level lies below the water level on apron,
the chances of horizontal eddies bringing the
sediments / riprap material back into the basin get
nullified.
2. The proposed stepped weir assures appropriate
location of jump for all operating conditions and thus
the corresponding Fr1 and energy dissipation is
maximum. This further reduces the chances of jump
sweep out in such situation.
3. The proposed basin requires no appurtenances like
chute blocks or baffle blocks. Thus there is saving in
their cost of construction.

References
• Achour, B., Debabeche, M. (2003). “Control of hydraulic
jump by sill in triangular channel”. J. Hydr. Res., 41(3), 319-
325.
• Anderson, J.D. (1995). “Computational fluid dynamics”.
McGraw-Hill book company, Inc., New York, 1995
• Chow, V.T. (1959). “Open channel hydraulics”. McGraw-Hill
book company, Inc., New York, 1959
• Hinge G. A., Balkrishna S., Khare K.C. (2010), Pawana Dam
Energy Dissipation – A Case Study, Australian Journal of
Basic and Applied Sciences, Vol.4(8), pp. 3261-3267.
• Hinge G. A., Balkrishna S., Khare K.C. (2010), Improved
Design of Stilling Basin for Deficient Tail Water, Journal of
Basic and Applied Scientific Research, Vol.1(1), pp. 31-40.

Hydraulic jump location control

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