1

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

2

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

3

Need for Improved DO in Reservoir Releases

4

“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

5

Prototype AVT, TVA’s Norris Plant, December 1994

6

Sectional View of Aerating Francis Turbine

7

Hydraulic and Environmental Performance

8

Measurement Difficulties

9

Typical Effects of Aeration on Efficiency Aeration Influence on Turbine Efficiency (Qw/Qwopt = 0.8)

-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 = 1.0)

-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)

10

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%)

11

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)

12

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

13

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.

14

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