SuperGen UK Centre for Marine Energy Research

Annual Assembly 2015

X-MED: EXTREME LOADING OF MARINE

ENERGY DEVICES DUE TO WAVES,

CURRENTS, FLOTSAM AND MAMMAL

IMPACT

.

UKCMER

PeopleManchester Plymouth Edinburgh SAMS

Stansby Greaves Bruce Wilson

Stallard Raby Bryden (now UHI) Benjamins

Apsley RA RA

Afgan Hann (now lect.) Payne

Rogers PhD

RAs Ransley

Feng

Longshaw

Rolfo

Ahmed

PhDs

McNaughton

Fernando

Rodriguez

Olczak

UKCMER

UKCMER

• WAVE ENERGY DEVICES

design sea states in waves and currents for a taut

moored floating body representative of a wave energy

device or support structure

• TIDAL STREAM TURBINES

1. tidal turbulence, wake turbulence in arrays

2. swell wave loading

3. impact of flotsam (containers) and marine animals

Objectives:

Requires simulation of: ambient turbulent flow,

ambient waves,

velocity and turbulence of wakes (of array)

effect of array on onset flow (channel blockage)

effect of array on waves Image: Olczak, 2015

Tidal Turbine Loading

Subject to ambient onset

Of in-array flow

Zero turbulence inflow

Synthetic turbulence (SEM) at inflow

Effect of turbulence on wake (LES)

Apsley, et al. Proc. 11th EWTEC. Sep 2015

LES no onset

turbulence

1 MW Alstom

Turbine at

EMEC

1 10 100

10−4

10−2

100

102

S(M

) FW

/ ò

S.d

f

f/f0

Blade tip/ root turbulence

Harmonics of

rotor frequency,

(shear and tower)

Onset

turbulence

Reasonable agreement to 1 MW data by LES with inflow turbulence by SEM

LES with SEM

Represents

full-scale

Ro

ot

Ben

din

g M

om

ent

No

rmal

ised

to

var

ian

ce

Apsley, et al. Proc. 11th EWTEC. Sep 2015

Effect of turbulence on blade bending.

12 % turbulence intensity

Turbulence only : 0.27 m Diameter

- Peak thrust in turbulent flow related to mean

17 % turbulence intensity

Fernandez 2015

Turbulent flow and opposing waves

Turbulence and waves: 0.27 m Diameter

- Thrust due to turbulence only and wave drag as:

Fernandez 2015

nose

waterproof

enclosure

torque and thrust

transducer

root bending moment

transducer

motor

rotary seal slipring

shafthub

Turbine to assess loads due to

Turbulence and Waves and Wake Scaling

Turbulence and waves: 1.2 m Diameter

Payne, et al. Proc. 11th EWTEC. Sep 2015

IFREMER tests 2015

4.5 5 5.5 6 6.5 7 7.5 80

0.1

0.2

0.3

0.4

0.5

CP

TSR

TI = 3%

TI = 12%

BEM

BEM high a

RANS−BEM

4.5 5 5.5 6 6.5 7 7.5 80

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

CT

TSR

TI = 3%

TI = 12%

BEM

BEM high a

RANS−BEM

Effect of turbulence on mean thrust and power

- Long run statistics and wave loads recorded

Payne and Stallard 2015

−0.2 0 0.2 0.40.5

1

1.5

2

1−Ux/U

0

y,z

Vertical

Transverse

−0.2 0 0.2 0.40.5

1

1.5

2

1−Ux/U

0

y,z

Vertical

Transverse

−0.2 0 0.2 0.40.5

1

1.5

2

1−Ux/U

0

y,z

Vertical

Transverse

−0.2 0 0.2 0.40.5

1

1.5

2

1−Ux/U

0

y,z

Vertical

Transverse

X = 0.1D X = 0.5D X = 1.0D X = 2.0D

Near-field wake

Vertical expansion constrained as small 0.27 m rotor.

Velocity Deficit

1R

Payne and Stallard 2015

22kN load cell

High tensile spring

And angular speed measurement

‘Blade’ (square section)

Target: PTFE with rubber ‘skin’

(same material as Minke whale model)

Impact rig to test force range and load cell

Payne, et al. Proc. 11th EWTEC. Sep 2015

Plastic target with rubber ‘skin’

Incre

asin

g t

arg

et m

ass

30 40 50 60 70 80 90 100 1100

2000

4000

6000

8000

10000

12000

14000

RPM

max

imum

im

pac

t fo

rce

(N)

1.6kg rubber

1.6kg plastic

4.4kg rubber

4.4kg plastic

Impact – variation with material and mass ,

repeatability

Payne, et al. Proc. 11th EWTEC. Sep 2015

In-array loading due to wakes

−2 0 2 4 6 8 10 12−5

−4

−3

−2

−1

0

1

2

3

4

5

0.93

0.91

0.94

0.75

0.80

0.79

0.74

0.89

0.57

0.57

0.58

0.89

0.90

0.89

0.91

0.69

0.65

0.71

0.66

0.84

0.42

0.45

0.48

0.98

1.00

1.00

1.00

0.94

0.89

0.89

0.94

0.99

0.69

0.67

0.69

0.99

1.00

1.00

1.00

0.78

0.78

0.90

0.71

0.96

0.65

0.67

0.65

0.87

X/D

y/D

(I) (II)

−0.2 0 0.2 0.4 0.6−5

−4

−3

−2

−1

0

1

2

3

4

5

1−Ux/U

0

y/D

(I)

−0.2 0 0.2 0.4 0.6−5

−4

−3

−2

−1

0

1

2

3

4

5

1−Ux/U

0

y/D

(II)

RANS-BEM Prediction

and Experimental Measurement

Prediction of mean thrust of multiple turbines in shallow turbulent flow

Assessed for one-, two- and three-row arrays. Olczak, et al. In review, Sep 2015

Wave – body dynamics

Taut moored buoy in COAST basin

Hann, M., Greaves, D., Raby, A. 2015 ‘Snatch loading of a single taut moored floating

wave energy converter due to focussed wave groups’

Ocean Engineering,96 (2015) 258–271

UKCMER

Open FOAM in 3D

Non snatch loads in focussed waves

E. J. Ransley (2015). Survivability of Wave Energy Converter

and Mooring Coupled System using CFD. PhD Thesis.

Plymouth University, UK

ISPH with FK forcing and

empirical added mass

Snatch loads , non breaking

waves

With breaking waves snatch loads overestimated ,

initially by 30%

Parallel and related research:

- Reliable Data Acquisition Platform for Tidal (ReDAPT) commissioned and

funded by the Energy Technologies Institute (ETI) and led by Alstom Ocean

with flow data collection by University of Edinburgh.

- Performance Assessment of Wave and Tidal array systems (PerAWaT)

commissioned by the Energy Technologies Institute and led by DNV-GL.

- ALLT-T: Arrays of long-life Turbines for Tidal (EPSRC-NEWTON)

- PhD projects funded by CONACYT, EPSRC UKCMER.

Additional funding and access to high performance computing by EDF.

Access to UK HPC via UKTC.

Acknowledgements

Impact by SPH-LSM

THANKS AND QUESTIONS