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Presented byPatrick A. March
Principal Consultant, Hydro Performance Processes Inc.
EPRI /DOE Conference on Environmentally-Enhanced Hydropower Turbines
May 19-20, 2011Washington Court Hotel, Washington, DC
Hydraulic and Environmental Performanceof Aerating Turbines
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Overview of Presentation
● Brief History of Aerating Turbines●Description of need for DO improvements● Turbine venting and hub baffles●Auto-venting (i.e., self-aerating) turbines
● Hydraulic and Environmental Performance●Measurement difficulties●Performance under aerating and non-aerating conditions
● Environmental Optimization of Aerating Turbines● Recommendations
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Need for Improved DO in Reservoir Releases
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“Streamlined” Hub Baffles (Norris, Pre-AVT)
Flat Plate Baffle
vacuum breaker opening
bar stock (typ)
trailing edge of turbine bucketflow
flow
vacuum breaker opening
section of schedule 40 pipe
Streamlined Baffle
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Prototype AVT, TVA’s Norris Plant, December 1994
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Sectional View of Aerating Francis Turbine
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Hydraulic and Environmental Performance
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Measurement Difficulties
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Typical Effects of Aeration on Efficiency Aeration Influence on Turbine Efficiency (Qw/Qwopt = 0.8)
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0
5
10
15
20
0 1 2 3 4 5 6 7 8
Qa/Qw (%)
Dec
reas
e in
Tur
bine
Effi
cien
cy (%
)
Distributed AerationCentral AerationPeripheral AerationLinear Extrapolation (Central Aeration)Linear Extrapolation (Distributed Aeration)Linear Extrapolation (Peripheral Aeration)Case Study (Central Aeration)Case Study (Distributed Aeration)Case Study (Peripheral Aeration)
Aeration Influence on Turbine Efficiency (Qw/Qwopt = 1.0)
-5
0
5
10
15
20
0 1 2 3 4 5 6 7 8
Qa/Qw (%)
Dec
reas
e in
Tur
bine
Effi
cien
cy (%
)
Distributed AerationCentral AerationPeripheral AerationLinear Extrapolation (Central Aeration)Linear Extrapolation (Distributed Aeration)Linear Extrapolation (Peripheral Aeration)Case Study (Central Aeration)Case Study (Distributed Aeration)Case Study (Peripheral Aeration)
Aeration Influence on Turbine Efficiency (Qw/Qwopt = 1.2)
-5
0
5
10
15
20
0 1 2 3 4 5 6 7 8
Qa/Qw (%)
Dec
reas
e in
Tur
bine
Effi
cien
cy (%
)
Distributed AerationCentral AerationPeripheral AerationLinear Extrapolation (Peripheral Aeration)Linear Extrapolation (Distributed Aeration)Case Study (Distributed Aeration)Case Study (Peripheral Aeration)
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Example: Challenges for Optimization Net Head Efficiency Test Results (Central and Distributed Aeration)
Net Head = 95 ft
0.70
0.75
0.80
0.85
0.90
0.95
1.00
1.05
1.10
10 15 20 25 30 35 40
Turbine Output (MW)
Nor
mal
ized
Net
Hea
d Tu
rbin
e Ef
ficie
ncy
2002 Upgraded Unit, Central Aeration Off
2002 Upgraded Unit, Central Aeration On (Qa/Qw = 2.7% to 4.4%)
Original Unit, Central Aeration Off
Original Unit, Central Aeration On (Qa/Qw = 0% to 3.1%)
2008 Upgraded Unit, Distributed Aeration Off
2008 Upgraded Unit, Distributed Aeration On (Qa/Qw = 5.0% to 7.4%)
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TDG Effects on Unit Order and Efficiency
Overall Plant Efficiency Curves (Gross Head = 95 ft)
65
70
75
80
85
90
95
0 50 100 150 200 250 300
Power (MW)
Opt
imiz
ed P
lant
Effi
cien
cy (%
) for
Spe
cifie
d U
nit O
rder
Typical Winter Ops (AC,AH,VH)
Optimized Winter Ops (VH,AC,AH)
Overall Plant Efficiency Curves (Gross Head = 95 ft)
65
70
75
80
85
90
95
0 50 100 150 200 250 300
Power (MW)
Opt
imiz
ed P
lant
Effi
cien
cy (%
) for
Spe
cifie
d U
nit O
rder
Typical Summer Ops (AH,VH,AC)
Optimized Summer Ops (VH,AC,AH)
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75
80
85
90
95
0
2000
4000
6000
8000
10000
12000
14000
16000
-50 0 50 100 150 200 250 300 350 400
Opt
imiz
ed P
lant
Effi
cien
cy (%
)
July
2010
-Ene
rgy
Hea
d 95
Power (MW)
Actual vs Optimized Energy
Aerating Operation
Scheduling for Efficient Operation
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Recommendations for the Hydro Industry
● Turbine manufacturers, agencies, and utilities should provide access to existing hydraulic and environmental performance information for aerating turbines.
● Industry should establish a national database of hydraulic and environmental performance data for aerating turbines: ● Funded by DOE, USACE, or EPRI, or other appropriate sponsor(s) ● Maintained by a national laboratory with related experience, such as Oak Ridge
National Laboratory.● Additional performance information should be solicited for the small
“minimum flow” turbine installations with DO enhancement.● ASME PTC-18’s efforts to develop a comprehensive test code for
aerating turbines should be financially supported by the hydropower industry.
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Recommendations for Additional Research
● Conduct long term monitoring and data analyses for aerating turbines to provide performance results over a wide range of conditions
● Improve aeration scaling relationships between physical models and prototypes
● Improve models for predicting gas transfer and resulting DO and TDG levels
● Improve models for predicting draft tube effects on turbine efficiency under aerating and non-aerating conditions
● Develop and demonstrate cost-effective DO enhancement options for Kaplan and bulb turbine units
● Develop and improve environmental optimization tools● Develop cost-effective methods to measure DO in reservoir releases