PARALLEL JETS EMERGING FROM MULTIPLE GATES: DISTINGUISHING FLOW CONDITION By Mohammad Bijankhan Salah Kouchakzadeh Gilles Belaud 5th International Junior Researcher and Engineer Workshop on Hydraulic Structures Spa, Belgium, 28-30 August 2014 1
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PARALLEL JETS EMERGING FROM MULTIPLE GATES: DISTINGUISHING
FLOW CONDITION
By
Mohammad Bijankhan
Salah Kouchakzadeh
Gilles Belaud
5th International Junior Researcher and Engineer Workshop
on Hydraulic Structures
Spa, Belgium, 28-30 August 2014
1
INTRODUCTION
Gates are widely used in irrigation networks in order
to adjust the upstream depth and discharge or to
measure the flow rate.
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“Omidieh” Irrigation network located at the
south part of Iran
INTRODUCTION
For a single gate the classical hydraulic jump can
be used to distinguish the flow condition (Lin et
al. 2002):
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INTRODUCTION
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INTRODUCTION
Wide channels
Parallel gates
It is suggested to keep all gates under free flow
condition (Clemmens 2004) 5
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“Omidieh” Irrigation network located at the
south part of Iran
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Three gates installed in parallel located in Pakistan
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Three radial gates and a weir installel in parallel, Salt
River project (Clemmens 2004)
INTRODUCTION
Practical gats’ configurations:
1. gates with different openings;
2. some gates are in operation and others are
closed.
3. The case for which the gate openings are the
same is less practical (Clemmens 2004).
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Practical gats’ configurations:
1.
2. gates are in operation and others are
3. case for which the gate openings are the
Clemmens 2004).
Practical gats’ configurations:
gates with different
some gates are in operation and others are
closed.
The case for which the gate openings are the
same is less
Practical gats’ configurations:
openings;
gates are in operation and others are
case for which the gate openings are the
Clemmens 2004).
Practical gats’ configurations:
with different openings;
gates are in operation and others are
case for which the gate openings are the
same is less practical (Clemmens 2004).
“SefidRud” Located in the North of Iran
OBJECTIVES
Applicability of the single gate distinguishing
condition to two parallel gates
Interaction between jets
Deriving the distinguishing condition curve for
two parallel gates
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METHODOLOGY
Experimentation
Employing momentum balance
Numerical modeling using OpenFoam (Ongoing
research)
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EXPERIMENTATIONS
University of Tehran
Two gates with different
openings.
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SupAgro, Montpellier
One closed gate;
ADV measurements.
wR/wL=1
wR/wL=1.4
wR/wL=1.88
wR/wL=3.35
Left
Gate
Right
Gate
CLASSICAL HYDRAULIC JUMP LIMITATION
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Left Control Volume
Right Control Volume
Left
gate
Right
gate
Classical Hydraulic Jump
Two jets with different Froude Numbers
Neglecting the interaction between jets
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Flow
CLASSICAL HYDRAULIC JUMP LIMITATION
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CLASSICAL HYDRAULIC JUMP LIMITATION
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CLASSICAL HYDRAULIC JUMP LIMITATION
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Right Control Volume
Closed
gate
Right
gate
Flow
HYDRAULIC JUMP DUE TO PARALLEL JETS
Hydraulic jump features:
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Right
Gate
Left
Gate
HYDRAULIC JUMP DUE TO PARALLEL JETS
Hydraulic jump features:
(a) Semi classical hydraulic jump
(b) Oblique hydraulic jump
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OBLIQUE HYDRAULIC JUMP
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2.5 1.03
DERIVING THE DISTINGUISHING
CONDITION CURVE
Momentum balance applied between the
supercritical jets and tailwater sections
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2 22 2 2 21, 1, 2
21, 1, 22 2 2
L L L RL R
L R
b y b yQ Q Q BygA gA gA
Control
Volume
Left gate
Right gate
DERIVING THE DISTINGUISHING
CONDITION CURVE
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W
W
Left Gate
Right Gate
W
wR=W(1+) and wL=W(1) 2
R Lw wW
=0 (Single gate)
=1 (One closed gate)
R L
R L
w ww w
RwLw
DERIVING THE DISTINGUISHING
CONDITION CURVE
Neglecting the approach velocity and head loss
energy formula would be:
Neglecting 2 (First order Taylor development),
and 2=1
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1 cy C W
( ) 1 ( ) 0 1 ( )2 ( )L R L R L RQ by g y y
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2 01
1
2 1yFry
DERIVING THE DISTINGUISHING
CONDITION CURVE
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2( ) 1 0.29 0.42 0 0.54J
( ) 0.7 1J
DERIVING THE DISTINGUISHING
CONDITION CURVE
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DIFFICULTIES AND FURTHER
DEVELOPMENTS
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Where should be positioned as the tailwater section?
1- A section far downstream the gate
Negligible value of the momentum correction factor
Is it possible to neglect friction forces?
How far it should be?
2- A section just after the jump
Considerable value of the momentum correction factor
Control
Volume
Left gate
Right gate
Control
Volume
Left gate
Right gate
DIFFICULTIES AND FURTHER
DEVELOPMENTS
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The submergence threshold also depends on the
measuring location at the tailwater section
CONCLUSIONS
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1- Classical hydraulic jump definition can not be
used for the parallel gates;
2- For the parallel jets it is necessary to consider
the jet interactions;
3- Momentum balance can be used to formulate the
submergence threshold;
4- Further studies is modeling the jet interactions
with OpenFoam to find the necessary corrections
and to answer the question about the tailwater
position.
Thank you for your attention
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