1. Presented By
A.M.P. Jayamanne

2.  Sri Lanka has huge potential of wave power
 Small frequency variations
 Plenty of sites
 Can use as a break water
 Less environmental impact
 Medium rough sea conditions

3. Propose Oscillating Water Column (OWC) wave
extractor.
 Promising and proven technology
 Simple structure
 Less links from wave to turbine which causes the
loses minimum
 Total concrete collector

4. Turbine
Chamber
Oscillating water
column
Incoming Water
waves

5. The 400 kW Oceanlinx wave powered generator off the coast at Port
Kembla NSW Australia

6. Use wells turbines because it generates torque in one
direction even air flow is bidirectional.
A low pressure air turbine
Hub
Generator
Rotor
Stator
Pilot valve

7. Partial Moving
path
Water surface
Sallow water
Zero Crossing
time
Wave height
Deep water
Total energy (P)= Kinetic energy + potential energy
P = [ρg2 /64π]*H2 T ≈ 0.5 H2 T (kw/m)
H = significant wave height = 4* standard deviation of water surface elevation
T = Zero crossing wave time period

8. 0
10
20
30
40
50
60
70
1 2 3 4 5 6
PKW/m)
Month
Bundala
0
2
4
6
8
10
12
14
16
1 2 3 4 5 6 7 8 9 10 11 12
PkW/m
Month
Dodandoova
0
10
20
30
40
50
60
70
80
90
1 2 3 4 5 6 7 8 9 10 11 12
P(kW/m)
Month
Godayaya
0
10
20
30
40
50
60
70
80
90
100
1 2 3 4 5 6
P(KW/m)
Month
Palatupana
Best Site – Godayaya
Mean significant wave height –2.8m
Zero crossing time – 11.05 - 13.34
Mean zero crossing time – 12.23

9. Air way
Added
damping/turbine
Applied
damper/friction
Floating water
mass
Wave force
Wave entrance
Buoyancy spring
Applied
spring/viscosity
Displacement
Collector

10.  Applied wave force due to the traveling of wave in to the cession = F e(t).
 Water column displacement for an instant time = y
 Instant time = t
 Applied damping coefficient due to friction =  f
 Applied damping coefficient due to turbine =  t
 Added water mass = m a
 Floating water mss = m f
 Applied spring coefficient due to water mass = ks
 Buoyancy spring coefficient = kb
 d = 1/2( ma + mf ) x [(4 ma
2 g2 -  t
2) / 4 ] ½
( ma + mf ) d2y/dt2 +  t dy/dt + kb y = F e(t).

11. Procedure
 Match actual frequency to model frequency and wave forcers
 Compare available plants for Sri Lankan conditions
 Select best plant
 Scale it to model willing to build
 Structural and turbine design.
Results
 Best plant – NEL ( Developed by Lanchester University and
Polytechnic)
 Scale Factor - 9.5

14.  Wells turbines have low efficient rates
 Effective energy can captured from waves to
generator is around 12%
 Reduces performance due to high frequency
changers
 Collector profile or volume has to change due to
incoming wave frequency and amplitude changers
 Sri Lankan wave climates are giving positive
behavior to OWC plants.
 Need to do more involvement to success