S.Salter@ed.ac.uk
S.Salter@ed.ac.uk
Second Oxford Tidal stream Workshop 2013
Are Nearly all Tidal Stream
Turbines Designs Wrong?
Stephen Salter
Institute for Energy Systems
University of Edinburgh
S.Salter@ed.ac.uk
www.see.ed.ac.uk/~shs
No names, no pack drill.
S.Salter@ed.ac.uk
. . . just like wind turbines but under water.
P max
1
2
3 16
 AU 
27
Frederick Lanchester 1868-1946 Albert Betz 1885-1968
Unswept flow passage ≡ leaky pipes
≡ Vortex wake pollution
≡ Ignorance of flow angles
O’Doherty DM. Mason-Jones A, Morris C, O’DohertyT, Bryne C, Pricket PW,
Grosvenor RI.
Interaction of marine turbines in close proximity.
EWTEC 2011
3
 2.75  0.55


 3.35
O’Doherty DM. Mason-Jones, Morris, O’DohertyT, Bryne, Pricket, Grosvenor.
Interaction of Marine Turbines in Close Proximity. EWTEC 2011
R.A. McAdam, G.T. Houlsby, M.L.G Oldfield. Structural and Hydrodynamic Model
Testing of the Transverse Horizontal Axis Water Turbine. EWTEC 2011
R.A. McAdam , G.T. Houlsby , M.L.G. Oldfield
Structural and Hydrodynamic Model Testing of the Transverse
Horizontal Axis Water Turbine
EWTEC 2011
Open flow field
Duct
1
3 16
Pow   AU 
2
27
Pow   gAH U
3
.296U
gH U
http://www.google.co.uk/search?q=Tidal+stream+turbine+Alstom&hl=en&client=safari&rl
s=en&tbm=isch&tbo=u&source=univ&sa=X&ei=BOBOUbPSJY6o0wXh2ICIBw&ved=0CE
IQsAQ&biw=1042&bih=1505
Bending moment at
blade root
GOOGLE IMAGES
NASA
EWTEC Patras 1998
Edinburgh vertical-axis, variable-pitch with rim power take off.
Pitch variation gives control of rotor forces
Contra-rotation cancels cross force and torque reaction in wake
D ow nst ream force on a 1 40 di amet er rot o r as a fract io n o f id eal
1.2
1.2
1
0.8
fds i 4
FDSi 4
0.6
0.4
0.2
0
0
 70  60  50  40  30  20  10
 DR
2
0
Xi
10
20
30
40
50
60
DR
2
70
Work goes through
restricted passage to congested
generation space
Second Oxford Tidal stream Workshop 2013
Are Nearly all Tidal Stream
Turbines Designs Wrong?
Stephen Salter
Institute for Energy Systems
University of Edinburgh
S.Salter@ed.ac.uk
www.see.ed.ac.uk/~shs
Google images
Google images
Speed up x 30
Range up x 6000
Payload up x 20,000
Cost per ton-mile down ÷ 100
Something for the simpletons
Laminaria Hyperborea
(kelp) are found along the
edges of the Pentland Firth
at depths up to 30 m.
Length can reach 3.5
metres.
Cf = ?
Google images.
68 mm
bob
Pentland bed stills. P Hayes. Fisheries Research Aberdeen 2006-8
Friction coefficients for Fshear = 0.5 ρ U2 Cf
6.165 TW x 0.04 = 247 GW
EWTEC Patras 1998
Edinburgh vertical-axis, variable-pitch with rim power take off.