Upload
balakumaran-natarajan
View
220
Download
0
Embed Size (px)
Citation preview
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 1/32
Wave loads on fixed offshore windturbines
Johan Peeringa en Erik-Jan de Ridder
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 2/32
2
Foundation types in 30 MW+ offshore wind farms
– 14 Monopiles
– 7 gravity bases
– 1 Tripod andJacket
List of offshore wind farms - Wikipedia, the free encyclopedia
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 3/32
3
Dowec 6MW
– Pitch regulated variablespeed
– Rated power 6MW
– Rotor diameter 129 m
– Hub height 91.4 m
– Monopile 6 m diameter
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 4/32
4
Selected frequencies of the Dowec 6MW
[Hz] [rad/s]
Tower for aft 0.242 1.521
Blade flat wise 0.675 4.241
Blade edge wise 1.107 6.956
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 5/32
5
Offshore wind turbine standards
Organisations
– GL – DNV
– IEC
Design situation IEC61400-3
– Power production (+ fault) – Start up
– Normal shut down
– Emergency shut down
– Parked (+ fault)
– Transport assemblymaintenance and repair
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 6/32
6
Linear and nonlinear waves
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 7/32
7
Wave models and wave loads
– Irregular linearwaves
– Nonlineardeterministicstreamfunction wave
–
Morison equation
Source: www.noordzeewind.nl
dz x x D
C dz x D
C dF D M
24
2
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 8/32
8
Breaking waves
– Blyth
– Wienke
Source: Jan v/d Tempel 2006
Source: Wienke 2001
IMDwave_break F F F F
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 9/32
9
Need for validation of wave load models onoffshore wind turbines
– Code to Code Comparison
– Lack of (public) full scale measurements
– Lack of model tests including hydroelasticity
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 10/32
10
Introduction
– ComFlow
– Linear wave theory vs stream function andComFlow
– Effect relative fluid velocity due to towermotions
– 1st
model tests – ..
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 11/32
11
ComFlow
– Volume of fluid CFD code
– Used at MARIN for: – Green water on deck
– Wave impacts
– Sloshing
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 12/32
12
ComFlow: example
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 13/32
13
Non linear wave forces using ComFlow
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 14/32
14
12m 8s @ 30m waterdepth
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 15/32
15
Influence of hydroelasticity
– Simple bending model
– Linear wave theory – Morison loading, including
relative velocities due totower velocity
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 16/32
16
ComFlow (CFD) does not (yet) include relativefluid velocity due to tower motions
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 17/32
17
Existing MARIN knowledge on segmentedmodels
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 18/32
18
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 19/32
19
1st step by MARIN
– Model tests with a flexible model
– No detailed modelling of the proto type (DOWEC6MW)
– The clamping flexibility of the foundation is partlytaken into account
– The 1st
and 2nd
natural frequencies are modelled, bytuning the weight distribution over the height
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 20/32
20
Full scale model
– DOWEC 6 MW turbine
– Tower 80 m – Support 30 m
– Water depth 21 m
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 21/32
21
FE analyses of model
– FE package ANSYS
– Analyses of model (scale 1:30) – 11 beam & 6 mass elements
– Clamping flexibility included
Tower
support
E , m , I1 2 2
E , m , I1 1 1
M2
M3
M4
M5
M6
EI
M1
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 22/32
22
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 23/32
23
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 24/32
24
Natural frequencies
Natural mode FE analyses Model testing
1st mode 0.26 Hz (1.4 Hz model) 0.59 Hz
2nd mode 1.77 Hz (9.7 Hz model) 2.23 Hz
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 25/32
25
– Accelerations at5 location
– Pressuremeasurementsat five location
– Forces andmoments at the
bottom
– Wave height atthree locationsaround the tower
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 26/32
26
Model set-up in the basin
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 27/32
27
Picture model tests of wave impact
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 28/32
28
First results model tests
– Acceleration at the top of the towerWave:
Hs= 5 m
Tp= 12s
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 29/32
29
First results model tests
– Acceleration at the top of the towerWave:
H= 14 m
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 30/32
30
2nd possible (step)tests
– The results can be used to validate numerical
software: – Which than can be used to optimise the control
system
– Optimised the turbine for specifiek locations
(waves point of view)
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 31/32
31
4th step full scale measurements
8/7/2019 Fixed Wind Turbine Website
http://slidepdf.com/reader/full/fixed-wind-turbine-website 32/32