1. Faculty of Science, Engineering & Technology
Optimising Hydropower Generation
Through Fluid Dynamics Research
Dr Jessica Andrewartha*, Dr Jane Sargison, Xiao Lin Li
School of Engineering, University of Tasmania, Australia

2. Faculty of Science, Engineering & Technology
Presentation Overview
Introduction
• Hydropower in Tasmania
• What is biofouling?
Efficiency Improvements in Hydropower Pipelines
Physics of Flow over Biofilms
• Real
• Artificial
Mitigation & Control
Summary & Conclusions
Repulse Dam, Derwent River, Tasmania

3. Faculty of Science, Engineering & Technology
Introduction
• Majority of electricity in Tasmania produced
by 29 hydropower stations
• Potential for hydropower in Australia well
exploited – now looking at efficiency
improvements
• Hydropower stations require transport of
water – sometimes over long distances (20 +
km)
• Tunnels, canals, flumes, pipelines &
penstocks – susceptible to biofouling
• UTAS / Hydro / ARC 10 year research
collaboration on biofouling Tarraleah Penstocks, Tasmania

4. Faculty of Science, Engineering & Technology
Introduction
Biofouling is the undesirable growth of biological
matter at liquid – solid interfaces
Global problem – causes large drag penalties
3 categories: www.crestock.com/image/131228-Barnacle-Texture.aspx
• Low-form gelatinous (slimes)
• Filamentous
• Hard deposits
Natural biofilms consist of one or more
components

5. Faculty of Science, Engineering & Technology
Efficiency Improvements in
Hydropower Pipelines
Why clean?
• Remove biofouling from internal surface
• Reduce effective wall roughness
• Improve hydraulic efficiency (i.e. reduce headloss)
Process: Pre-clean test
↓
Clean internal surfaces by
high pressure water
blasting
↓
Post-clean test

6. Faculty of Science, Engineering & Technology
Efficiency Improvements in Hydropower Pipelines
What was measured:
• Pressure at US and DS locations • Water level (ultrasonic depth sensors)
(pressure transducers)
• Water temperature
• Flow rate (ultrasonic flowmeters)
• Machine characteristics

7. Faculty of Science, Engineering & Technology
Efficiency Improvements in Hydropower Pipelines
Power Scheme Details
Wilmot Tungatinah Poatina Tarraleah
Penstock Penstock 4 Penstock Hilltop Pipeline
Output (MW) 35 125 300 90
Operating head (m) 252 300 835 299
Pipeline length (m) 526 877 1684 2141
Penstock diameter (m) 1.98 1.7 - 2.3 2.6 – 3.1 2.6
Improvement in 1.0 0.8 - 2.0
Headloss (m)

8. Faculty of Science, Engineering & Technology
Efficiency Improvements in Hydropower Pipelines
• Biofilms increase headloss
• Gains in energy production can be made by
removing biofouling
• Data plotted on a Moody diagram is not typical of
engineering roughness
• Moody diagram extensively used in industry to
predict friction losses
• More data over wider range of Reynolds numbers
is needed
• New pipe rig at UTAS will be used to gather this
data
• Rig in field to grow biofilms
• Rig in lab for detailed testing

9. Faculty of Science, Engineering & Technology
Physics of the Flow
over Biofilms
Do flows over biofilms
conform to same structure as
for typical engineering
surfaces?
• Grew biofilms on 1m x 0.6m
test plates in hydropower
canal
• Drag measurements and
boundary layer profiles in
water tunnel
• Characterised roughness
using photogrammetry

10. Faculty of Science, Engineering & Technology
Physics of the Flow over Biofilms
• Biofilms increase skin
friction drag (measured up
to 99% increases)
• No change to mean velocity
structure
• Changes to turbulence
structure only very close to
the wall
• Biofilms thicker on plates
with rough surface
• Drag coefficient roughly
linear function of max peak-
to-valley height of biofilm

11. Faculty of Science, Engineering & Technology
12.0
Flow over Artificial Biofilms Streamers: black
Smooth: red
U = 1.0, 1.25, 1.75, 2.0 m/s
• Skin friction increased by 23% 8.0
(U-u)/u*
• No change to mean velocity structure
4.0
• Turbulence intensity increased by 50% in
region y > 1 mm out to freestream
0.0
• Streamers change turbulence structure 0.0 0.5 1.0 1.5
(y+ )/
• Working on capturing motion using high- 12.0
speed cameras
• Find frequency of oscillation 8.0
(%)
u' 2 U
4.0
0.0
0.0 0.5 (y+ )/ 1.0 1.5

12. Faculty of Science, Engineering & Technology
Mitigation & Control
• Dewater & physically remove fouling with brooms
attached to tractors
• High pressure water blast in pipelines
• Chemical and heat treatment methods ineffective
– majority of biofilm is dead cells and inorganic
material
• Long term mitigation
• Provide as smooth a surface as possible
• Increased wall shear – difficult for biofilms to
establish
• Trials of different surface coatings – some
perform better than others

13. Faculty of Science, Engineering & Technology
Summary & Conclusions
• Significant improvements to efficiency &
generating capacity can be made by removing
biofilms
• Control of biofouling is a global problem, and not
just in hydropower
• Current research – understanding wall flows with
complex organic interacting surfaces, rather than
typical engineering roughnesses
• Climate change policy will see greater investment
in renewable energy technologies

14. Faculty of Science, Engineering & Technology
Acknowledgements
This research was funded by:
• 3 Australian Research Council Linkage Grants
• Hydro Tasmania
• University of Tasmania New Appointees Research
Grant
The authors also gratefully acknowledge:
A. Barton, K. Perkins, G. Walker, A. Henderson, J.
Osborn, A. Leith, G. Hallegraeff, P. Brandner,
workshop staff at UTAS, and the many staff at Hydro
Tasmania involved in the project.