Embed Size (px)
Citation preview
1
Physical and numerical modeling of
the spillways and plunge pools of
Koman Dam in Albania
Etude sur modèle physique et numérique
des évacuateurs de crue et des fosses
d‘érosion du barrage de Koman en Albanie
Giovanni De Cesare Milad Daneshvari
Matteo Federspiel Mathias Malquarti
Gaël Epely Chauvin Anton Schleiss
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Contents
• Dam location, introduction, problem
• Layout and scale of physical model
• Numerical Model
• Results and discussion
• Summary and conclusions
2
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Dam location - Albania - Drin River
3
Koman
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Dam location - Drin River cascade
4
• Conrete faced Dam
• 115 m high
• Built between 1980 and 1988
• Installed capacity 600 MW
• Two tunnel spillways with ski jump
• Spillway No. 3, capacity 1'900 m3/s
on left bank
• Spillway No. 4, capacity 1'600 m3/s
on right bank
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Downstream view of Koman dam
5
No 3
No 4
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Dam toe erosion and plunge pool size
6
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Dam location - local satelite view
7
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Physical model - overview
8
• Froude model, scale 1:65
• Mobile bed topography
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Physical model - sediment details
9
Prototype :
Loose material of river bed: 0 – 100 cmd50 = 11 cm and d90 = 56 cm
Model grain size for representing
in-situ rock mass: 8 – 16 mm50 % (volume) : 8 - 11 mm (blocks of 52 cm to 72 cm)
50 % (volume) : 11 - 16 mm (blocks of 72 cm to 104 cm)
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Physical model - discharge scenarios
10
Ten different discharge scenarios
• Spillway No.4
• Spillway No.3
• Spillway No.3 & No.4
simultaneously:
Scenario 1 Scenario 2 Scenario 3 Scenario 4
25% discharge 50% discharge 75% discharge 100% discharge
400 m3/s 800 m3/s 1'200 m3/s 1'600 m3/s
Scenario 5 Scenario 6 Scenario 7 Scenario 8
25% discharge 50% discharge 75% discharge 100% discharge
475 m3/s 950 m3/s 1‘425 m3/s 1‘900 m3/s
Scenario 9 Scenario 10
50% discharge 100% discharge
1'750 m3/s 3'500 m3/s
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Physical model - measurements
11
• Water level and velocity in the spillways
• Flow at spillway outlet and jet trajectory
• Water depth and velocity in the plunge pool
• Flow circulation in the plunge pool
• Bed load movement and scouring
(mound is not removed)
• Ultimate scouring depth (mound is removed)
• Wave action and dynamic pressure at the dam toe
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Numerical model - Flow3D
12
• Flow-3D finite volume approach
• Numerical domain consists of rectangular boxes
with rectangular cells
• Staggered grid arrangement (velocity on cell
faces, other variables at cell centre)
• Fractional Area-Volume Obstacle Representation
(FAVOR) method for geometry representation
• Closure for turbulence k- model
• Model with fixed (plunge pool) bottom
• Model with mobile bed
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Numerical model - geometry
13
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Results - jet trajectories
14
Jet trajectory
Spillway No. 3
100% capacity,
1'900 m3/s
Jet compression due to
the non deflected upper
layer reduces trajectory
length
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
40
60
80
100
120
140
0 20 40 60 80 100 120 140 160 180 200
Alt
itu
de
[masl
]
Horizontal distance [m]
Lower jet layer - theoretical
Upper jet layer - theoretical
Lower jet layer - phys. model
Upper jet layer - phys. model
Initial flat sediment surface - phys. mod.
Ultimate scour hole in the model
Plunge pool bottom - site observation
Results - jet trajectories
15
Jet trajectory, Spillway No. 4, 100% capacity, 1‘600 m3/s. Observed
trajectory on the physical model and theoretical value. Jet travel
length is reduced by 12 m. Good prediction of plunge pool geometry
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Video of real jet
16
Jet trajectory
Spillway No. 4
10% of
capacity only !
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Results - jet impact and pressure
17
Jet impact zone measured
with fixed grid, as well as
pressure inside jet
• The jet has no more well defined core
• large lateral spreading
• form of a twirl or banana
• due to ski jump geometry
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Results – plunge pool
18
Ultimate scouring depth (The mound is removed)
Spillway No.4, Q=1’600 m3/s, maximum scour depth: 20 m (56 masl)
Site observations (Mai 2010) Physical model
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Results – plunge pool
19
Ultimate scouring depth (The mound is removed)
0
20
40
60
80
100
120
140
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360
Ele
vati
on
[m
asl]
Station [m]
Ultimate scour hole in the model in comparison with site observation
(longitudinal profile through spillway No.4 axis)
Site observation
Ultimate scour hole in the model
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Results - erosion with Flow-3D
20
First tests performed with Flow-3D using simple, symmetric
geometry with data from Pagliara et al. (2008), JHE
Dimensionless
scour hole depth zm
as function of log( )
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Results – plunge pool Flow-3D
21
Modeling with mound in place, spillway No. 4, 1’600 m3/s
Physical model
Numerical modelProfondeur d'érosion [m] Hauteur du dépôt aval [m]
Résultats de la modélisation numérique physique numérique physique
Fosse d'érosion à l'aval de l'évacuateur No. 4 0.135 0.108 0.092 0.123
Fosse d'érosion à l'aval de l'évacuateur No. 3 0.138 0.154 0.013 0.123
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
Summary and conlcusions
22
• Koman dam in Albania has downstream erosion
problems due to spillway operations
• Physical and numerical modeling as well as
extensive on-site observation have been performed
• Good agreement of all major results
• Non optimal functioning of ski jump deflection
• Plunge pool scour hole close to dam toe, in addition
to extensive wave action on dam toe and left bank
• Validation of sediment erosion and transport model
in Flow-3D with literature
• Successful application to real case study
De C
esare
et al.
Physic
al and n
um
erical m
odelin
g o
f th
e s
pill
ways a
nd
plu
nge p
ools
of
Kom
an D
am
in A
lbania
The end
23
THANK YOU
Questions ?
