di Lorenzo, E.

Horcas, S.G.

Martinez, J.

Mehdi, R.

Mehta, D.

Pereira, Gilmar Ferreira

Soman, R.

Online Research Database In Technology

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Downloaded from orbit.dtu.dk on: Dec 20, 2017MARE-WINT: New Materials and Reliability in Offshore Wind Turbines TechnologyHorcas, S.G. ; di Lorenzo, E. ; Martinez, J. ; Mehdi, R.; Mehta, D.; Pereira, Gilmar Ferreira; Soman, R.Published in:Proceedings of 10th EAWE PhD Seminar on Wind Energy in EuropePublication date:2014Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Horcas, S. G., di Lorenzo, E., Martinez, J., Mehdi, R., Mehta, D., Pereira, G. F., & Soman, R. (2014). MARE-WINT: New Materials and Reliability in Offshore Wind Turbines Technology. In Proceedings of 10th EAWE PhDSeminar on Wind Energy in Europe (pp. 192-195). European Academy of Wind Energy. The aim reliability of(O&M) strategies’ [1].Researchersundertaken 1.  OrganizationsMAREreliability, andresearch is carried out in the context MARE  distributed between various project’son optimizing the same reference wind turbine, aspect of MARE structure of the paper is unorthodoxConclusion, the paper is divided into sections tWork Packages New Introduction Improving In As-WINT is one s-WINTM  tof the    by a selection ofAREsix his conference paper has been prepared MaEuropean Commission funded MARE[offshore](ESRs)  such as the European  optimize the operation is -work packages are structured  terials & 1World Maritime University the rethe DTU (Technical UniversitWINT, the tasks of -WINT. 1 to 510thImproving the Reliability andS.G.Horca, spread across Table 1 .  PhD Seminar on Wind Energy in Europe wind turbines The project is divided into sevenliability of offshore wind turbinesuch project.   ESR’Cut–researchers, with each researcher working in a specific  Res, E. di Lorenzo, J. Rotor orientation, configuration-in, Rated, CutOverhang, Shaft Tilt, Pre Specifications of the DTU 10 MW Reference Wind Turbines in MARE TCutliability in Offshore  (OWTs)17 institutes [2Commissionhe aim of MARE and maintenanceof aRotor, Hub Diameter-in, Rated Rotor Speedfurther , Maritime Risk & System Safety (MaRiSa) Group -out Wind SpeedRated Tip Speed. Instead of MARE Optimising-reference wind turbineDescriptionHub HeightRotor MassNacelle Tower Massas shown in the following figure.   Martinez, R and their componentsWINT.y of Denmark) 10 MW Reference Wind TurbineControlDrivetrainPreoptimizing various components of the wind turbine system are hat detail the work under progress in each of the A are Rating-Cone-bendMasscollaborationfor an entire project, rather- O&M Strategies for Offshore Wind Turbines BSTRACT-WINT project is to ‘reduce ].    funding various project-WINT                typical   –                      WINT. Mehdi  This paper of offshore Value10 MWUpwind, 3 bladesVariable Speed, Collective PitchMedium Speed, Multiple Stage Gearbox178.3m, 119m4m/s, 11.4m/s, 25m/s6RPM, 9.6RPM90m/s7.07m, 53m229 tons (Each Blade ~ 41 tons)446 tons605 tons   28 work packages is curr          -31 1, D. Mehta, Gas mentioned . 5.6m, 2.5    and sections such as Introduction, Discussion, and October                   :  Wi,describes some of the current work being ently an area of greatwind turbine The reference wind turbine under research Fig.1:Reference Wind Turbine. Source: [4] nd  and optimizing operation and maintenance    cooperation between is an important core  Method         20T.  (WPs) 14,  urbines TechnologyPereiras and researchers in the domain;aboveSince all t than an individual researcher Orléans, France, , and betweens. . Source [3]followed by DTUR. Soman, rm@wmu.secost of energy is In order to fulfill this aim   essentially,Work Package he researchers are working        research (RWT) for, by improving  15 tovarious designing the   Early Stage  improve the . (WP).  interest.   project  , The , the the  in  192/199               2. WP 1 – Innovative Rotor Blades (ESR 1 & 2)  ESR 1’s task includes modelling of manufacturing defects in OWT blades; the aim of ESR 1 is to develop the damage tolerance approach in wind turbine blade sub-structures, focusing on the crack growth mechanisms and detection methods. The trailing edge of the blade can develop damage in the composite material and adhesive interface. The delamination is accompanied by the formation of a crack bridging zone, where intact fibers connect the crack faces behind the tip thus increasing the energy required for crack propagation (Damage tolerance mechanism) [6]. A finite element model of the crack growth mechanisms in a double cantilever beam (DCB), representative of the trailing edge, was developed where different fracture modes were addressed. Experimental tests were conducted in order to fully characterize this structure and support the model. Then a crack monitoring technique was implemented using Fiber Bragg Grating (FBG) sensors in order to track the crack tip and its’ propagation. This sensor approach was incorporated with the finite element model in order to predict the sensor output and extrapolate to a real trailing edge case. Experiments were conducted on DCB specimen crack growth with FBG monitoring under several fracture modes.  The focus of ESR 2 is on CFD investigations of near-blade 3D flow for a complete OWT configuration. The current work of ESR 2 is not covered further in this conference paper.                             3. WP 2 – Drive Train & Gearbox (ESR 3 & 4)  The gearbox is one of the key subsystems in a geared wind turbine providing the task to transfer power from the low speed shaft connected to the rotor to the high speed shaft connected to the genera3or. As turbines become larger, more power is demanded and gearboxes with higher load capacity need to be designed. A deep knowledge into gearbox dynamics becomes of fundamental importance and noise and vibration measurements are demanded.  ESR 3’s task involves simulation & experimental validation of drive train loads for offshore specific conditions. Like ESR 2, further details of this task are not covered in this paper.  The task of ESR 4 primarily involves the derivation of a strategy for model updating based on experimental data from drive train test facility. Since several components properties depend on the applied torque and on the rotational shaft speed, a validation in operational conditions needs to be performed. Building on existing techniques such as “Order Tracking” and “Operational Modal Analysis”, a dedicated methodology is going to be developed, by ESR 4, for the analysis of operational gearbox dynamic behavior. Particular attention will be reserved to the separation between structural resonances and excitation orders.  Operational Modal Analysis (OMA) is used by ESR 4 to derive an experimental dynamics model from vibration measurements in operational conditions. It cannot be applied in a straightforward way due to the self-induced vibrations at several rpm-dependent frequencies (gear meshing orders). These frequencies can be wrongly considered resonance frequencies of the system. In order to face these problems, an extensive measurement campaign has been performed at ZF Wind Power on a 13.2MW test rig facility [1] (Fig.1). Accelerations have been measured at more than 250 locations on the test rig and for different load levels and operating conditions. For stationary conditions (at constant rpm) the gear meshing orders will give component discrete constant frequencies that need to be filtered out from the signal in order to determine the resonances. Run-up tests can be considered as a multi-sine sweep excitation and the resonances can be identified combining advanced order tracking methods with operational modal analysis by using a dedicated methodology, named Order-Based Modal Analysis (OBMA). The developed algorithms will be evaluated by means of flexible multi-body simulation models and real experimental data.  Fig.2 – The ‘Structure’ of the Work Packages in MARE-WINT. Source: [5] Fig. 3: Investigating the presence of damage in blades, understanding damage propagation mechanism  & providing solutions for more reliable structure design using new materials, processes, and sensorisation. ESR 1  193/199         4.  concept, anfocudescription of the work carried out by ESR 5 & 6 is omitted from this paper.  5.  ESR 8’s Filter based Neutral Axis trackinghence encompasses the selection of the damage detection feature,optimal information using minima resources, signal processing and the damage detection.  are proposed for the damage detection. The damage detection in towers is carried out using the change in neutral axis (NA) position as the damage sensitive feature while in blades the use of The is independent of the loading conditions thus through the use of strain sensors we can track the location NA accurately and any change in the location of the NA will be an indication of damage. In order to account for the change in the mass orientation of the wind turbine due to the yawing of the nacelle a data fusion strategy using extended Kalmanthe presence of measurement   reasonably accurmeasurements as the input and yields the NAE location as an estimate. The use of EKF improves the prediction of the NA and as such gives robustness performance of the damage deallows us to fuse data. The future plan is to incorporate the rotation of the wind turbine in the data fusion strategy to allow online damage detection in actual working conditions.slightly complicated due to the composite materials and the complex geometry. Furthermore embedding the sensors inside the blade is a problem, thus the use of IR thermography and using remote sensing is being investigated. detection. The proposed methodology will be validated on experimentally available data and FE models of the structure available. implementation of KFESR 1011a and 11bresearchers is not covered in any further detail in this paper.   WP 3The task of s on bottom fixed substructure analysis, model testing and design for harsh environment.WP 4ESR 7Due to the different nature of the materials NA of a beam like structure is the property of the cross section of the structure and its condition, and hence ESR 8Fig. 5 (L to R)& the metric is sensitive to even small extents of damage and shows robustness to presence of measurement noise.  ESR 9’s research has a focus on – d to compare the results –  research focuses on’, through his Offshore Support StructureReliability & Predictiveaimss methodology was applied on a FE model of the 10MW DTU reference wind turbine and yields The entire study are carrying out research ESR 5 to addressate damage detection. The use of EKF uses the strain measurements and yaw angle : Flexural Strain Distribution over the beam cross ; Nu is to develop  filtmerical research er (EKF) was proposed in [7                                       OWT condition monitoring damage detection in metallic & composite noise and temperature changes [8 undertaken in the task will focus on structural health monitoring for online damage Model of the Tower. , . ESR 8’s task tries to setup a damage detection strategy at the saims to reduce navigational risk assessment of vessels operating near OWTs, dynamic modelling and analysis of a floating wind turbine with laboratory test data or field measurements Maintenance (ESR 7, 8, 9, 10,  on AnalysisInitial investigations have shown promise in the technique to detect damage,  wake effect fatigue loads usioverall used in the structures two different damage detection strategies  (ESR 5 & 6) OWT reliability modelling analysis. based on acoustic emission and long range ultrasonic. ]. The EKF yields robustness to the NA tracking even in  Fig 6Energywake aerodynamics fatigue on offshore wind farms -secti  ].  The damage detection strategieson subject to eccentric loading;Fig. 4Tracking & Operational Modal Analysis techniques, to develop a new method, and validate it by means of numerical models (flexible MBS model) & experimental data (test rig measurement : -Conserving Schemes to study wind farm Using Large Eddy Simulation with 11 optimisationtection strategy in noisy environments and : Building further on existing Order a & 11bstructures elastic waves is being investigated. ng Large Eddy Simulations (LES).). ESR 4towards predicting loading &)  through the use of Kalman  of sensor placement to get  . ESR 9. ESR 6  Flow Chart for the    The by contrast, will ystem level and  for blades are work of these  A detailed  ESR 8Lastly,  of the   . ESRs  194/199 6. WP 5 – Fluid Structure Interaction (ESR 12, 13 & 14)  ESR 12’s task involves RANS simulation for hydro-elastic floating substructure prediction. Horcas, et al. [9], summarize ESR 12’s work as ‘a new development aiming to deform multi-block structured viscous meshes during fluid solid interaction simulations. The focus will be put on the deformation of external aerodynamic configurations accounting for large structural displacements and 3D multimillion cells meshes. In order to preserve the quality of the resulting mesh, it was understood as a fictitious continuum during the deformation process. Linear elasticity equations were solved with a multi-grid and parallelized solver, assuming a heterogeneous distribution of fictitious material Young modulus. In order to improve the efficiency of the system resolution an approximate initial solution was obtained prior to the elastic deformation, based on Radial Basis Functions and Transfinite interpolators. To validate the performances of the whole algorithm, the DTU 10MW reference offshore wind turbine described by [10] is analyzed’.   ’s research focuses on analysis of a twist-coupled aero-elastic design for passive loads reduction on ESR 13a full scale blade. Further details are not provided in the current paper.   is carrying out investigations into active flow control to improve aerodynamic performance using ESR 14 blade modelling & high quality grid generation. ESR 14 looks forward to achieve an aerodynamic performance improvement of wind turbine blades by decreasing the flow separation and associated noise in real time. This goal will be reached through the implementation into the 10 MW MARE-WINT wind turbine reference of a new rod vortex generator technology that in its MEMS configuration allows an active control. Due to the lack of experimental data for the reference turbine, the 2 bladed 10 m rotor diameter NREL UAE Phase VI wind turbine was selected for validation purposes. A considerable effort was put into the geometry modelling and grid generation for obtaining the high quality structured mesh adequate for the flow study. The upwind and downwind boundaries were located three blade radius away from the rotational plane. The farfield was situated at the same distance from the rotational axis.  In Fig. 7 below, the definition of the domain boundaries for the simulation can be found. At the inlet the static temperature and velocity were specified, meanwhile the static pressure was imposed at the outlet. The blade was defined as Navier-Stokes adiabatic wall.  The RANS simulations were done employing both, Spalart-Allmaras and SST k-w models. Good agreement was found between experimental and numerical data. In the figure 2 the Cp distribution along the chord for a couple of sections for a 7 m/s inflow speed are shown as example. Once validated through the numerical methods, the vortex generators will be implemented in the NREL blade and their aerodynamic and aeroacoustic effects studied.            Fig. 7 (L to R): Grid domain; blade geometry with tip detail; Cp distributions along the cross sections 95% & 63% for 7 m/s. ESR 14  7. Conclusions  work and research in MARE-WINT is on-going, with project deliverables due in September 2015 . This Thepaper has presented the results of only a selection of the researchers and research activities. Even the limited results shown in the paper, however, indicate a promising level and quality of knowledge and information. There is utmost confidence that the current and future results from MARE-WINT will be used to improve the reliability of offshore wind turbines, and optimize the operations of the system as a whole.  REFERENCES [1][2][5] http://marewint.eu/ - last accessed on 30th May 2014, 17.00 CET [3][4][10] C.Bak, F.Zahle, R.Bitsche, T.Kim, A.Yde, L.C.Henriksen, M.H.Hansen, J.P.A.A.Blasques, M.Gaunaa, A.Natarajan, The DTU 10-MW Reference Wind Turbine. Danish Wind Power Research 2013, Fredericia, Denmark (2013). Related data publicly available at http://dtu- 10mw-rwt.vindenergi.dtu.dk/  [6] Bent F. Sørensen, “Cohesive laws for assessment of materials failure: theory, experimental methods and application. Doctor of technices thesis, Risø-R-1736(EN) [7]Soman, R, Malinowski, P and Ostachowicz, W. Neutral Axis Tracking for damage detection in wind turbine towers, In: Proceedings of the EWEA 2014, Barcelona, Spain. 10-14 March 2014. [8]Soman, R, Malinowski, P and Ostachowicz, W. Kalman-filter based data fusion for neutral axis tracking for damage detection in wind-turbine towers, In: Proceedings of the EWSHM 2014, Nantes, France. 7-12 July 2014. [9] Horcas S G., Debrabandere F., Tartinville B., Hirsch Ch., Coussement G., ‘Mesh Deformation Tool for Offshore Wind Turbines Fluid Structure Interaction’, In: Proceedings of WCCM XI, ECCM V, ECFD VI, 20 – 25 July 2014.  195/199

MARE-WINT: New Materials and Reliability in Offshore Wind Turbines Technology

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MARE-WINT: New Materials and Reliability in Offshore Wind Turbines Technology

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