low-frequency second-order drift-forces experimental ... · set 1: pink noise (0º & 20º...
TRANSCRIPT
Low-frequency second-order drift-forces
experimental validation for a Twin Hull
Shape Offshore Wind Platform - SATH
The Company
Introduction to SATH concept
Model testing motivation
Experiments
Numerical validation
Main conclusions
2
Layout
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
3 EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
SATHTM INNOVATIVE FLOATING WIND SOLUTION
MAKING OFFSHORE WIND GLOBAL
Spin-off from International Infrastructure engineering company
Designing the future
Patented technology
CO
MP
AN
Y P
UR
PO
SE
The Company
4
Introduction to SATH concept
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
Floaters - Buoyancy
Heave plates - Motion dampers SPM – External turret Self-alignment with the Wind Direction - Stresses reduction
Transition piece -Interface tower-floater
CONCRETE LOW DRAFT SELF-STABLE
Swinging Around Twin Hull
Reduced construction and maintenance costs
2 MW – 6.5m 10 MW – 9.5m
Easily transportation
Internal bulkheads - Load transmission
5
Model testing motivation
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
OBJECTIVE
LIMITATIONS
METHODOLOGY
Collaboration Project
NUMERICAL CALIBRATION
Mooring System optimization
Potential theory assumptions
EXPERIMENTS at IFREMER (July 2018) - Mean Drift Coefficients extraction - Full-QTF Coefficients extraction
FAST
Sima
6
Experiments
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
Scale model
Wind turbine Computer-controlled
Qualysis Track motion
Load cells mooring system
Scale model 1/36 Full
prototype-2MW
Length (m) 1.72 61.92
Width (m) 0.85 30.6
Total height (m) 2.05 73.8
Draft (m) 0.2 7.35
Total Mass (kg) 82.8 3863116.8
7
Experiments
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
Soft Mooring Simple an linear setup for identification
of hydrodynamic coefficients.
Experiments set-up
VCG to decouple the pitch motion from
the mooring system forces.
8
Experiments
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
Calibration of waves
Test campaign planning
Tests in waves: periodic; irregular; pink noise Characterization tests: decay; tilt; pull out
Identification of mass properties
9
Experiments
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
Characterization tests – Global verification of the structure behaviour
Natural oscillation periods
Metacentric heights
Mooring stiffness
Linear & Quadratic damping
Saitec X (m) Trans GM(m) Long GM(m)
Stiffness (K)
10
Experiments
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
Tests in waves– Periodic waves
Extraction of the Mean Drift force Coefficients for different
incidence angles and wave steepness
OBJECTIVE
K = mooring stiffness measured (N/m) X = mean displacement measured (m) F = mean drift force (N) A = wave amplitude (m)
Wave elevation (m)
Stiffness curve (K/mm)
Surge (mm)
11
Experiments
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
Tests in waves– Periodic waves Test Matrix:
Set 1: head waves; no wind; different steepness Set 2: head waves; wind influence; Set 3: 20º waves; no wind;
Real model
Period Height Steepness
6.000 1.116 0.020
6.000 4.680 0.083 7.980 1.692 0.017
7.980 4.320 0.043
7.980 8.640 0.086
9.000 2.088 0.016 9.000 5.256 0.042
9.000 10.512 0.083
10.000 2.900 0.019
10.980 7.992 0.043
10.980 15.984 0.086
13.020 4.392 0.017
13.020 11.016 0.043
13.020 19.800 0.078
16.500 7.488 0.020
16.500 15.480 0.042 Potential theory over-estimates the coefficients Favourable steepness dependency
12
Experiments
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
Tests in waves– Irregular waves
Extraction of the full Quadratic Transfer Function coefficients
OBJECTIVE Second order signal analysis technique based on cross bi-spectral analysis
13
Experiments
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
Tests in waves– Irregular waves Test Matrix:
Set 1: pink noise (0º & 20º incidence) Set 2: sea-states along the 50 years environmental contour (0º & 20º incidence) Set 3: sea-states representative of operational conditions (0º & 20º incidence)
Favourable steepness dependency
0
10
20
30
40
50
60
70
0,04 0,06 0,08 0,10 0,12 0,14 0,16
F (
kN
/m2)
f (Hz)
Surge wave drift force coefficients (0 deg.)
Potential flow
Test 1117 (df = 0.007 Hz)
Test 1080 (df = 0.007 Hz)
Test 1119 (df = 0.007 Hz)
Test 1107 (df = 0.007 Hz)
Test 1109 (df = 0.007 Hz)
Test 1113 (df = 0.007 Hz)
Test 1105 (df = 0.007 Hz)
Test 1115 (df = 0.007 Hz)
0.02
3 0.01
9
0.01
2 0.01
9
0.03
6 0.03
7
0
20
40
60
80
100
120
0,00 0,10 0,20 0,30
F (
kN
/m2)
f (Hz)
Surge wave drift force coefficients (0 deg.)
Potential flow
Test 1117 (df = 0.007 Hz)
Test 1070 (df = 0.007 Hz)
Test 1080 (df = 0.007 Hz)
Test 1119 (df = 0.007 Hz)
Test 1107 (df = 0.007 Hz)
Test 1109 (df = 0.007 Hz)
Test 1113 (df = 0.007 Hz)
Test 1105 (df = 0.007 Hz)
Test 1115 (df = 0.007 Hz)
Test 1111 (df = 0.007 Hz)
14
Numerical validation
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
Extraction of the Mean Drift Force Coefficients from tests
Correction of potential flow Mean Drift Coefficients f(steepness)
Time Domain Simulations using Newman’s Approximation
Frequency Domain Simulations (Based on potential theory)
Optimization of the mooring system design
15
Numerical validation
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
Hs = 5m Tp = 8.8s
16
Numerical validation
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
Hs = 7m Tp = 11s
17
Numerical validation
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
Hs = 9.4m Tp = 13s
18
Numerical validation
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
Hs = 9.7m Tp = 18s
19
Numerical validation
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
Hs = 9.7m Tp = 16s
20
Numerical validation
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
Hs = 5m Tp = 13s
21
Numerical validation
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
22
Numerical validation
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
23
Main conclusions
EERA DeepWind’2019| Araceli Martínez · Saitec Offshore Technologies | January 2019, Trondheim, Norway
• Soft mooring set-up – Simplifications of results
• Only wave tests – No extra phenomena (wind or current)
• Duration of the tests – 3 hour sea-states
• Wave tank basin characteristics – No reflection
• Potential theory – Over-estimation of the results
• SATH Technology – Non-linear response for different wave steepness
• Newman’s Approximation – Verified for SATH concept
• Optimization of the mooring system – Adjustment of numerical models