Canadian Dam Association Bulletin - Spring 2018 - 23

8.0
Orifice #2

Orifice #3

Site C Theoretical (HWL = 425 m)

Orifice #4

Site C Theoretical (HWL = 435 m)
Site C Theoretical (HWL = 440 m)

7.0

Orifice #1

Incipient - Scale Effect (Site C)

Cavitation Coefficient

Incipient Cavitation - Model

6.0

5.0

4.0

3.0

0.64

0.66

0.68

0.70

0.72

0.74

0.76

0.78

Orifice Diameter Ratio

0.80

0.82

the assumed prototype
incipient cavitation line.
The cavitation performance was considered
acceptable with the index
dropping just below the
theoretical incipient line
due to the short duration
of operation at this maximum design level and the
conservatism of designing
for incipient cavitation for
a temporary structure. The

incipient level was used as the design
criteria for the permanent orifice
tunnel at Xiaolangdi. The orifices for
Site C are temporary structures that
are needed for 2 to 4 weeks of total
operating time during the first stage
of reservoir filling. As discussed in
Section 7, local cavitation is anticipated downstream of the orifice lip
or in the main body of the flow at the
shear plane where high pressure fluctuations were observed in the PHM.
Local cavitation in the body of the

Figure 11 - Site C Cavitation Coefficient Scaling

model scales as well as a largescale model test performed in a
3.8 m diameter tunnel at the Bikou
Hydropower Station.
* The "Incipient - Scale Effect (Site C)"
line represents the assumed prototype incipient cavitation line for Site
C using the Xiaolangdi model test
line as a baseline, scaled up using
the relationship documented in
Lin, 2003.
* The "Site C - Theoretical" points
indicate the theoretical cavitation
indices for the four Site C orifices
at three different water levels
(El. 425 m, 435 m, 440 m) covering
the range that would be experienced
during reservoir filling.
* The diameter ratio (β) of each of
the four orifices were designed to
balance the cavitation performance at the maximum operational
level 440 m.
The following key conclusions can
be drawn from the cavitation plot in
Figure 11:
1. The Site C theoretical cavitation
indices remain at or above the
theoretical incipient cavitation line
for Site C for almost the full range
of reservoir levels required for the
first Stage of reservoir filling.
2. The Site C theoretical cavitation
indices reach the incipient cavitation line near the maximum reservoir level. At lower levels, there
is a significant margin of safety
between the orifice cavitation indices and incipient cavitation.
3. The cavitation indices at maximum
operating reservoir level of 440 m
are well balanced in comparison to
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12/05/17 23
12:47 AM


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Table of Contents for the Digital Edition of Canadian Dam Association Bulletin - Spring 2018

Board of Directors
President’s Message
Site C Clean Energy Project Diversion Tunnel Orifices for Energy Dissipation During Reservoir Filling
Application for 2018 CDA Scholarships
CDA Presents 2017 Scholarships
ICOLD Corner
CDA Conference 2018
EIC Awards Gala
Buyers’ Guide and Trade List
Canadian Dam Association Bulletin - Spring 2018 - 1
Canadian Dam Association Bulletin - Spring 2018 - cover1
Canadian Dam Association Bulletin - Spring 2018 - cover2
Canadian Dam Association Bulletin - Spring 2018 - 3
Canadian Dam Association Bulletin - Spring 2018 - 4
Canadian Dam Association Bulletin - Spring 2018 - 5
Canadian Dam Association Bulletin - Spring 2018 - 6
Canadian Dam Association Bulletin - Spring 2018 - Board of Directors
Canadian Dam Association Bulletin - Spring 2018 - President’s Message
Canadian Dam Association Bulletin - Spring 2018 - 9
Canadian Dam Association Bulletin - Spring 2018 - Site C Clean Energy Project Diversion Tunnel Orifices for Energy Dissipation During Reservoir Filling
Canadian Dam Association Bulletin - Spring 2018 - 11
Canadian Dam Association Bulletin - Spring 2018 - 12
Canadian Dam Association Bulletin - Spring 2018 - 13
Canadian Dam Association Bulletin - Spring 2018 - 14
Canadian Dam Association Bulletin - Spring 2018 - 15
Canadian Dam Association Bulletin - Spring 2018 - 16
Canadian Dam Association Bulletin - Spring 2018 - 17
Canadian Dam Association Bulletin - Spring 2018 - 18
Canadian Dam Association Bulletin - Spring 2018 - 19
Canadian Dam Association Bulletin - Spring 2018 - 20
Canadian Dam Association Bulletin - Spring 2018 - 21
Canadian Dam Association Bulletin - Spring 2018 - 22
Canadian Dam Association Bulletin - Spring 2018 - 23
Canadian Dam Association Bulletin - Spring 2018 - 24
Canadian Dam Association Bulletin - Spring 2018 - 25
Canadian Dam Association Bulletin - Spring 2018 - Application for 2018 CDA Scholarships
Canadian Dam Association Bulletin - Spring 2018 - 27
Canadian Dam Association Bulletin - Spring 2018 - CDA Presents 2017 Scholarships
Canadian Dam Association Bulletin - Spring 2018 - 29
Canadian Dam Association Bulletin - Spring 2018 - ICOLD Corner
Canadian Dam Association Bulletin - Spring 2018 - 31
Canadian Dam Association Bulletin - Spring 2018 - CDA Conference 2018
Canadian Dam Association Bulletin - Spring 2018 - 33
Canadian Dam Association Bulletin - Spring 2018 - EIC Awards Gala
Canadian Dam Association Bulletin - Spring 2018 - 35
Canadian Dam Association Bulletin - Spring 2018 - 36
Canadian Dam Association Bulletin - Spring 2018 - 37
Canadian Dam Association Bulletin - Spring 2018 - Buyers’ Guide and Trade List
Canadian Dam Association Bulletin - Spring 2018 - cover3
Canadian Dam Association Bulletin - Spring 2018 - cover4
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