An Investigation of River Kinetic Turbines: Performance Enhancements, Turbine Modelling Techniques, and a Critical Assessment of Turbulence Models

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An Investigation of River Kinetic Turbines
Performance Enhancements,Turbine Modelling
Techniques, and a Critical Assessment of
Turbulence Models
by David L. F. Gaden Department of Mechanical and
Manufacturing Engineering University of Manitoba
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Committee Members

• Dr. E. Bibeau (departmental advisor)
• Dr. A. Gole (Electrical Engineering)
• Tom Molinski (Manitoba Hydro)
• Dr. S. Ormiston (Mechanical Engineering)
• External Reviewer
• Mr. P. Vauthier (UEK)

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Outline

• Introduction
• Technology overview
• Recent kinetic hydro developments
• Wind energy literature review
• Shroud Optimisation
• Anchor Experiment
• Validation
• Conclusion
• Future Study

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IntroductionTechnology Overview
Geographic location with a natural flow
restriction
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IntroductionTechnology Overview
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IntroductionTechnology Overview
8 ft
Example of a kinetic turbine
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IntroductionTechnology Overview

• Advantages
• No reservoir or spillway minimal environmental
  impact
• Site selection far less restrictive
• No dams or powerhouses low cost installation
• Fast deployment times
• Modular easily scalable energy output
• Steady flow rates, steady energy production

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IntroductionTechnology Overview

• Disadvantages
• Possibly dangerous flow conditions
• No control over upstream conditions
• Turbulence, foreign debris
• Unknown fish mortality rate

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IntroductionRecent kinetic hydro developments

• Little in open literature for river kinetic
  turbines
• Purpose
• To develop modelling techniques for river kinetic
  turbines
• To understand the reliability of these models
• Use these models to evaluate performance
  enhancements for kinetic turbines

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IntroductionRecent kinetic hydro developments
1970
1980
1990
2000
UEK (Various)
Nova Energy, NRC (3 sites)
Nihon University (Japan)
Scottish Nuclear, IT Power (Scotland)
Northern Territory University (Australia)
Marine Current Turbines (UK)
Horizontal axis turbine
Vertical axis turbine
Ducted turbine
Adapted from Segergren, 2005
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IntroductionRecent kinetic hydro developments
1990
2000
Horizontal axis turbine
Vertical axis turbine
Ducted turbine
Adapted from Segergren, 2005
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IntroductionWind energy literature review
1980
1990
2000
THEORY
E x 3
THEORY
N x 4
THEORY
N x 3.2
E x 1
N x 5
E x 1.3
E x 1.25
THEORY
N x 2
THEORY Paper covers ducted turbine theory
N Numerical study
N x 2
x 3 Results show a power increase by a factor
of 3
E Experimental results
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Shroud OptimisationTheory
Conventional turbine
Small power available
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Shroud OptimisationTheory
Shrouded turbine
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Shroud OptimisationTurbine Modelling
Four turbine modelling strategies
1. No model
2. Momentum source
3. Averaging rotating reference frame
4. Sliding mesh rotating reference frame
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Shroud OptimisationTurbine Modelling
Four turbine modelling strategies
1. No model
2. Momentum source
3. Averaging rotating reference frame
4. Sliding mesh rotating reference frame
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Shroud OptimisationTurbine Modelling
Four turbine modelling strategies
1. No model
2. Momentum source
3. Averaging rotating reference frame
4. Sliding mesh rotating reference frame
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Shroud OptimisationTurbine Modelling
Four turbine modelling strategies
1. No model
2. Momentum source
3. Averaging rotating reference frame
4. Sliding mesh rotating reference frame
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Shroud OptimisationTurbine Modelling
Four turbine modelling strategies
1. No model
2. Momentum source
3. Averaging rotating reference frame
4. Sliding mesh rotating reference frame
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Shroud OptimisationMomentum Source
Design variables 1. Diffuser Angle
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Shroud OptimisationMomentum Source
Design variables 1. Diffuser Angle 2. Area ratio
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Shroud Optimisation Momentum Source
Model dimensions
Flow domain
Surface mesh
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Shroud OptimisationMomentum Source
Variable Area ratio
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Shroud OptimisationMomentum Source
Variable Angle
Power increase by a factor of 3.1 Drag
increase by a factor of 3.9
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Shroud OptimisationMomentum Source
Streamlines for 45 diffuser
Streamlines for 20 diffuser
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Shroud OptimisationMomentum Source
No diffuser versus diffuser
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Shroud OptimisationMomentum Source
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Shroud OptimisationMomentum Source

• If area is limited, shroud will reduce turbine
  size
• Shroud is still beneficial

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Shroud OptimisationRotating Reference Frame
Tetrahedral mesh
Flow domain
Hexahedral mesh
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Shroud OptimisationRotating Reference Frame
A.
B.
C.
D.
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Shroud OptimisationRotating Reference Frame
Relative power output
A.
B.
C.
D.
(standard)
100 46.4 kW
95.8 44.4 kW
84.7 39.3 kW
105.5 48.9 kW
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(No Transcript)
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Shroud OptimisationRotating Reference Frame
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Anchor Experiment

• Boundary-layer causes power loss

Velocity
y/d
U/U8
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Anchor Experiment
Anchoring System
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Anchor Experiment

• Four anchor models

3 m
A.
B.
C.
D.
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Anchor Experiment
At 7.5 m downstream from Anchor
P / P8
y / d
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Anchor Experiment
Midstream velocity contours
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Validation

• Particle Image Velocimetry (PIV) used
• Six experimental runs
• 2 configurations (nozzle diffuser)
• 3 flow speeds (0.5 m/s, 0.8 m/s and 1.0 m/s)
• For each, four CFD simulations performed
• 2 Eddy-viscosity turbulence models (k-e SST)
• 2 Reynolds stress transport models (SSG BSL)

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Validation
Water tunnel test section
Ruler (for alignment)
Model
Laser
Mirror
Camera
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Validation
PIV Apparatus
TEST SECTION AND MODEL
FLUID WITH SEEDING PARTICLES
LASER AND OPTICS
CAMERA
COMPUTER AND SOFTWARE
DATA ACQUISITION AND CONTROL SYSTEM
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Validation
Frame 1
Frame 2
d2
d1
d3
Raw Image
Both frames
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Validation
PIV Streamlines velocity contours
Diffuser, 1 m/s
Nozzle, 1 m/s
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Validation
k-e streamlines velocity contours
Diffuser, 1 m/s
Nozzle, 1 m/s
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Validation
SSG streamlines velocity contours
Diffuser, 1 m/s
Nozzle, 1 m/s
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Validation
k-e velocity error
Diffuser, 1 m/s
Nozzle, 1 m/s
47
Validation
SSG velocity error
Diffuser, 1 m/s
Nozzle, 1 m/s
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Validation
Full-field validation results
Root mean square error (RMSE) used to
evaluate each model across the entire field
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Validation

• PIV Experimental error
• Seeding particle density too low
• 5 particles / IA recommended (Dantec 2000)
• 3 particles / IA
• Velocity up to 55 under-read (Keane et al. 1992)
• Field of view too large
• Poor handling of high velocity gradients
• 60 probability of valid detection (Keane et al.
  1992)
• Regions with high gradients cannot be trusted

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Validation

• CFD inlet conditions inadequate
• Modelled as uniform flow, but it was not

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Conclusions

• River kinetic turbines are studied
• Shroud optimisation (momentum source model)
• Power increase by a factor of 3.1
• Sacrificing turbine area for duct can double
  power output
• Shroud optimisation (rotating reference frame)
• Cylindrical shroud can cause 30 power loss
• Power increase of 4 with a diffuser
• Power increase of 25 comparing against shrouded
  turbine

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Conclusions

• Anchor experiment
• Up to 90 power loss due to boundary layer
• Upstream flow obstruction can increase power
  available
• 30 power increase seen 12 meters downstream
• Geometries designed to maximize vertical
  disturbance were most successful

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Conclusions

• Validation
• Full field velocity RMSE of between 21.2 to
  47.4
• PIV experimental errors
• Low seeding particle density ? velocity
  under-read
• Small field of view ? lower probability of valid
  detection
• CFD modelling errors
• Inlet velocity assumed to be uniform
• Eddy-viscosity based turbulence models performed
  superior than Reynolds stress turbulence models

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Future Study

• Turbine rotor geometry
• Study of cavitation
• Mechanical and electrical losses
• Additional shroud optimisation study
• Further performance enhancements
• Wing design
• Inlet stators
• Improve the shroud validation validate the
  turbine model
• Study interactions with array installations
• Fish mortality and damage susceptibility

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Acknowledgments
Dr. Eric Bibeau Dr. A Gole Andrea Kraj Jeremy
Langner Manitoba Hydro Mr. T.
Molinsky NSERC Dr. S. Ormiston Dr. M.
Tachie Mr. P. Vauthier
Dr. Eric Bibeau Dr. A Gole Andrea Kraj Jeremy
Langner Manitoba Hydro
Mr. T. Molinsky NSERC Dr. S. Ormiston Dr. M.
Tachie Mr. P. Vauthier