Canadian Dam Association Bulletin - Spring 2018 - 25

flow away from the tunnel lining is
not anticipated to be a concern, and
the robust design and construction
of the orifices will minimize damage
downstream of the orifice lip.
Prototype and model measurements
performed for Xiaolangdi (Lin 2003)
indicated that incipient cavitation
was potentially an over-conservative
design criteria. Even though incipient cavitation was observed at a cavitation index of, for example, 4.65 at
Xiaolangdi, only very weak cavitation
was observed down to a cavitation
index of 3.80. This range of cavitation was reported to have no danger
of causing damage or reduction in capacity. Pressure results observed in the
Site C CFD model results shown in
Figure 6 also supported the conclusion that cavitation was successfully
mitigated with the final orifice design.

12. CONCLUSIONS
The Site C reservoir filling arrangement required a design to restrict
downstream discharges through the
north bank diversion tunnels while
maintaining minimum environmental
releases. A solution involving a retrofit of four in-line orifices into one of
the 10.8 m internal diameter diversion
tunnels was selected and optimized
through desktop calculations, utilization of information from model testing
and performance of a similar precedent, CFD modelling and PHM.
The head loss coefficient for each
orifice was verified through physical
modelling and determined to correlate well with the available reference
material; however, interaction between
orifices had a significant impact on
results. Model results indicated that
an orifice spacing of five times the
tunnel diameter ensured minimal
interaction. The cavitation coefficient is a key consideration for orifice
design. The potential scale effects
from model to prototype were carefully considered. Ensuring the design
does not fall below incipient cavitation levels is conservative, but until
further research and documentation
is available, the incipient level is the
recommended design criteria for the
governing hydraulic conditions. ■
Canadian Dam Association * Spring 2018

13. REFERENCES

Journal of the Hydraulics Division,

Croockewit, J., J. Bruce, F. Yusuf, J. Nunn and

HY 4. July, 1967.

A. Watson. 2017. "Site C Clean Energy

USBR (United States Department of the Interior -

Project General Hydraulic Features".

Bureau of Reclamation). "A Water Resources

Canadian

Technical

Dam

Association

Annual

Conference. Kelowna, British Columbia.

Publication,

Engineering

Monograph No. 42, Cavitation in Chutes and

October 16 - 18, 2017.

Spillways". April 1990.

Lin, X. S. "Multi-Well Plate Dissipation Spillway

Vischer D.L., and W.H. Hager. "Energy Dissipators".

Tunnel of Research and Engineering

IAHR Hydraulic Structures Design Manual

Practice". China Water Power Press. 2003

No. 9. 1995. Zhang, Q. Y. and B.W. Chai.

(in Chinese).

"Hydraulic Characteristics of Multistage

Russell, S.O., and J.W. Ball. "Sudden-Enlargement
Energy Dissipator for Mica Dam". ASCE

Orifice Tunnels". ASCE Journal of Hydraulic
Engineering. August 2001.

REVOLUTIONARY

WATERSTOP

SYSTEM FOR NEW & EXISTING

MONOLITH JOINTS
The long-term solution for leaking joints
in concrete gravity dams, powerhouses
and navigation locks.

LONG-TERM

SOLUTION

PREFERRED

PRODUCT

OF CHOICE

Contact us today for further information
1 541 504 0416 | www.emagineered.com

749175_Emagineered.indd 1

20/05/15 25
2:30 PM


http://www.emagineered.com http://www.emagineered.com

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
https://www.nxtbook.com/naylor/CDAQ/CDAQ0119
https://www.nxtbook.com/naylor/CDAQ/CDAQ0418
https://www.nxtbook.com/naylor/CDAQ/CDAQ0318
https://www.nxtbook.com/naylor/CDAQ/CDAQ0218
https://www.nxtbook.com/naylor/CDAQ/CDAQ0118
https://www.nxtbook.com/naylor/CDAQ/CDAQ0417
https://www.nxtbook.com/naylor/CDAQ/CDAQ0317
https://www.nxtbook.com/naylor/CDAQ/CDAQ0217
https://www.nxtbook.com/naylor/CDAQ/CDAQ0117
https://www.nxtbook.com/naylor/CDAQ/CDAQ0416
https://www.nxtbook.com/naylor/CDAQ/CDAQ0316
https://www.nxtbook.com/naylor/CDAQ/CDAQ0216
https://www.nxtbook.com/naylor/CDAQ/CDAQ0116
https://www.nxtbook.com/naylor/CDAQ/CDAQ0415
https://www.nxtbook.com/naylor/CDAQ/CDAQ0315
https://www.nxtbook.com/naylor/CDAQ/CDAQ0215
https://www.nxtbook.com/naylor/CDAQ/CDAQ0115
https://www.nxtbookmedia.com