www.ecn.nl

Wind Turbine Aeroelasticity

Training Course 2013

Mixed Training course being held on

11 - 13 November in Amsterdam

Contents (click hyperlinks)

o Welcome

o Aeroelasticity – an overview

o Course fly over

o Training module overview

o Detailed module explanation

o Schedule

o Venue

o Accommodation options

o Application

o Contact details

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Welcome

These slides have been sent to you to inform of the freshly updated ECN training course in Wind Turbine Aeroelasticity for professionals. The next mixed company session will be on 11 - 13 November 2013 in Amsterdam.

These slides introduce Aeroelasticity and its current importance during blade and turbine design. Additionally the modules of the course are explained along with what you can expect to learn from our expert trainers.

We anticipate that this training will be very relevant to your business. It is designed for you to speed up and improve your design process and lower risks in your blade design development, and deployment.

If you are interested in attending this course please fill out and return the application form.

Aeroelasticity – an overview

Aeroelasticity is the study of the mutual interaction that takes place between the inertial, elastic, and aerodynamic forces acting on structural members exposed to an airstream. This interaction has a significant effect on the actual fatigue loads of the turbine.

Increasing turbine size and cost drivers makes this discipline more and more relevant and evermore challenging. Ever since the 1990’s there have been documented cases of damage and loss of blades due to aeroelastic problems. Current trends in turbines are pushing us closer and closer to the different aeroelastic stability boundaries.

Knowing which instabilities to watch out for and understanding how to avoid or remove them, it is possible to prevent aeroelastic problems early in the design phase and reduce the costs and time of the design procedure.

In this course the participants will be provided with the necessary knowledge and gain some practical experience in avoiding excessive fatigue loads due to badly damped modes.

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Course fly over

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The course begins by providing a solid base from which to apply further learning on aeroelasticity. If you are relatively new to this field or are looking to recap on some of the fundamentals, then these subjects are essential. If you are rather more experienced you may choose to focus more time on other subsequent sessions. All the theory of Aeroelasticity is then fully explored and there will be plenty of time for questions and interaction. The best way of learning is by doing. In the last part of the course practical examples will be addressed. In the case of individual company training this is the best opportunity to address specific challenges you are facing. Please inform our trainers on day 1 of these items. In the mixed setting it is of course much more difficult, if not impossible to focus on specific problems that you may be facing in design process.

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8 7 6 5 4

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Aeroelasticity training

Module Overview

Introduction to Aerodynamics

Modules 1 and 2 introduce the essential elements of aerodynamics that are necessary to understand before moving ahead with other modules.

Module 1: BEM basics

The derivation of the BEM theory will be shown and explained. This module is recommended for participants with little experience in using BEM.

Module 2: BEM extensions

This module deals with the application of BEM to aeroelastic situations; i.e. how to take the dynamic blade deformations into account. For this purpose several corrections that exist for BEM theory are explained such as dynamic inflow models, dynamic stall models and yawed flow models. The actual wind input will also be addressed (turbulence, rotational sampling, etc.).

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Structural Dynamics

A second discipline that is relevant for aeroelasticity is the field of structural dynamics.

Module 3: Linear Vibrations

In this module the elastic deformations of beam structures will be discussed and the principle of eigenmodes will be explained. The derivation of eigenmodes of simple spring and mass structures is used as an example and the common eigenmodes for beams and blades are shown. The theory of linear vibrations will be explained, including resonance, beats, linear damping, etc.

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Theoretical Aeroelasticity

Modules 4, 5, 6, 7 and 8 deal with the theory under pinning aeroelasticity. This ranges from a general introduction to aeroelasticity to classical flutter. Both blades and turbines are covered.

Module 4: General Introduction to Aeroelasticity

A general introduction into aeroelasticity is provided before moving on to the more detailed aeroelasticity aspects.

Module 5: Resonances

Possible resonances are discussed. This includes resonances at tower frequencies and some possible resonances in the drive train.

Module 6: Blade instabilities

This module will explain the blade mode shapes, frequencies, as well as the theory of the instabilities and provide ideas of how to avoid or mitigate these problems from the design. 9

Theoretical Aeroelasticity

Module 7: Turbine mode shapes and instabilities

The wind turbine mode shapes are covered. These mode shapes are more complex than the blade mode shapes and the possible instabilities are also more complicated to explain and understand. The different modes will be explained and known instabilities are discussed.

Module 8: Flutter

Classical flutter is discussed in the final module in this subject. Next to the mechanism behind the instability, it is also explained how one can determine the speed at which flutter will occur.

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Implementing aeroelasticity

In modules 9, 10, 11 and 12 we put the theory into practice together.

Module 9: Load analysis

First there is an introduction into load analyses, how to perform these, what to look for and what post processing can provide additional valuable information.

Module 10: Solving blade instabilities

Participants will be challenged to identify and solve instabilities, first for blades…

Module 11: Solving turbine instabilities

….then for whole turbines.

Module 12: Structural Pitch

Finally there is a module that will focus on the importance of the structural pitch angle. The importance of this angle in the analysis as well as the opportunities it offers for the stability of the blade will be dealt with.

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Some examples from the course

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Example which is used to explain the different multi-blade modes on a wind turbine and how they will influence the tower. Frequencies are transferred from a rotating to a fixed

reference frame which sometimes results in a shift in the frequency.

Some examples from the course

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Example showing the damping of the edgewise and the flapwise blade mode. A simple aerodynamic model illustrates the basics and can be used to identify ways to improve the damping characteristics.

Schedule

Morning 9:00-12:00 Afternoon 13:00-16:00

Day 1 The modules BEM basics and BEM extensions will

be given.

The participants will be reminded of the basics of

BEM and the additional corrections that exist will

be explained.

The modules linear vibrations and introduction to

aeroelasticity will be given. Additionally a small

introduction to the code Blademode will be

provided, as this code will be used in some of the

other (interactive) modules

Day 2 The modules resonances and blade instabilities

will be given.

The participants will be introduced to the structural

pitch angle and do some investigations concerning

this using Blademode. Also some possible blade

instabilities will be solved by the participants

Day 3 The modules concerning turbine modes and

instabilities. The load analysis and how to

interpret the outcome will be explained.

The module explaining classical flutter in detail will

be given.

Finally, what to do concerning complete wind

turbine instabilities will be discussed.

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Venue and logistics

AMSTERDAM

The city of Amsterdam is very easy to reach via Schiphol airport or public transport. Car hire should not be necessary for you.

The training location is very accessible and only 5 minutes walking distance

from Amsterdam Sloterdijk train station.

Training address: Radarport gebouw Radarweg 60 1043 NT Amsterdam

Useful webpage links:

Trains: www.ns.nl

Public transport in Amsterdam: http://9292.nl/en

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Accommodation options

The training location means that you can take your pick of the many accommodation options in or around Amsterdam.

If you wish to have very easy access to Amsterdam city centre you may choose to stay in the central area of Amsterdam. It is only a 10 minute trip from Amsterdam Central station to the training venue.

www.tripadvisor.com or www.booking.com are good webpages to find possible accommodation options in various price categories.

If you need further information or assistance on accommodation you can contact our secretaries.

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Application

• Should you be interested please fill in and return the order form that is also supplied in this email.

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Contact details

• General and technical questions: – Jessica Holierhoek

– holierhoek@ecn.nl

– +31224564278

• Assistance with travel arrangements or advice: – Linda Zwart

– zwart@ecn.nl

– +31224564115

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