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Aeroelastic rotors in multibodyAeroelastic rotors in multibody simulation
Dr.-Ing. R. Schelenz,Dipl.-Ing. T. KamperDipl Ing S FlockDipl.-Ing. S. Flock
Aeroelastic rotors in Multibody Simulation
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Overview
Institute for machine elements (IME) Boundary conditions for the simulation Boundary conditions for the simulation Interconnections aerodynamic – rotor – drivetrain Simulation resultsSimulation results Summary Future prospects
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Institute for machine elements and machine design
Head of the Institute:
Univ.-Prof.Dr.-Ing. G. Jacobsg Chief-engineer transmission technology Chief-engineer tribology
25 scientific associates
ca. 80% financed by third-party funds
27 non-scientific staff
Machine-shop Measurement-engineering
Contact:IME
Machine-shop, Measurement-engineering, Administration
70 student assistantsSchinkelstr. 1052062 Aachenwww.ime.rwth-aachen.de
Reseach and teaching
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Institute for machine elements and machine design
Headline: Mechanical Drive TrainDivisions
Slide bearings Machine DynamicsTribology Transmission Technology
Rolling bearings
Freewheels
MBS
Torsional vibrations
FEM C l l ti Coatings
Lubricants
Filter & Oil systems
FEM-Calculations
Drivetrain-efficiency
AcousticsFilter & Oil systems cous cs
Gearbox Systems
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Interactions between the subsystems of a wind turbine
Aerodynamicsystem
Mechanical system (Focus on the Gearbox) Electrical system
Interaction InteractionInteraction Interaction
WEA Controller: DLL-Module
Aeroelastic rotors in Multibody Simulation
WEA Controller: DLL Module
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Interactions between the subsystems of a wind turbine
Expansion of the system-boundaries by taking intoaccount an elastic tower connected to the foundationaccount an elastic tower connected to the foundation.
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Aerodynamical load application
Feedback aerodynamics & elasticity:Measurement of the wind speed at one point:
Resulting incident flowg• Rotorspeed of the rigid rotor
• Wind measurement-pole / anemometer • Conversion to hub height
Alt ti N i l i d d &• Oscillating speeds of the
A d i l f
• Alternative: Nominal wind speed & specification of the turbulence
elastic rotor
Aerodynamical forcesDynamical rotor torque
Wind field-generator:
Id ll P ll l Fl• Ideally Parallel Flow• Yaw-missalignment• Altitude profile
Stochastic distribution of rotor area
Aeroelastic rotors in Multibody Simulation
• Stochastic distribution of rotor area
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Flow effects taken into account
Blade Element Momentum Method (BEM) For the calculation of the aerodynamic forces on the bladeprofile the enhanced blade
l t t th i delement momentum theory is used. The required polars for the blade profiles are determined either by experimental analysis
in wind tunnels or by simulations Good compromise between computing time and quality of the result Good compromise between computing time and quality of the result By expanding BEM, dynamic processes can be taken into account.
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Considered flow effects
Inflow due to Yaw misalignment The windspeed consists of a normal and a tangential component relative to the rotor plane The revolving blade moves periodical in and against the direction of the windg p g Due to the varying dynamic pressure the resulting force on the blade is subject to
fluctuations Furthermore the relative position of the blades to the wake of the leading blade varies withp g
time
Dynamic inflow / stall The blade element method does not consider
any time delay of the systemresponse in case of a change of the inflow→ By adding a „Dynamic inflow model“ to BEM, unsteady flow effects can be modelled
I f t ll th fil th d i In case of a stall on the profile, the dynamic coefficients do not conform to the coefficients in the polar→ Implementing of a „Dynamic stall models“
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Considered flow effects
Influence of height Integration of different methods, to
consider a change of the windspeed over theconsider a change of the windspeed over the height of the wind energy plant.
Tower pile-up / Tower shadow The piling up of the flow in front of the tower leads to a
massive reduction of the blade forces and hence themassive reduction of the blade forces and hence the propulsive torque.
Representation of the flow around the tower as a (drag afflicted) cylinder flow(drag afflicted) cylinder flow
Oscillational excitation of the rotor blades
Tip LossTip Loss The pressure gradient on the rotor blade causes a compensating flow around the blade tip A part of the kinetic energy can not be used for torque generation
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Integration of elastic components
The FEMBS-Interface in SIMPACK enables the integration of FE-Models The dynamical behavior of the component can be reduced to a set of
eigenfrequencies by a modul reduction
Nodes for the a application of the aerodynamic loads
Reduction of the computing effort
First rotor-eigenmodes:Ed i (f 1 9 H ) Fl i (f 1 1 H )
Rotor section
Edge wise (f7 = 1,9 Hz) Flap wise (f5 = 1,1 Hz)
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Modelling
Wind turbine Controller Active pitch control Dynamic control of the generator-torque,
the generator-state and the braking torque
Specification of the air gap torque by a Specification of the air-gap-torque by a characteristic curve of the doubly fed asynchronous generator
Integration of the wind turbine controller
Rotor with elastic bladesRotor with elastic blades Flexible machine support Complete MBS transmission with elastic
structure elements like rotorshaft orstructure elements like rotorshaft or planet carrier
Integration of linear & bending modes with high relevance to the torsional DGF
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Validation of simulation models (component wise)
Example: planet carrier (D ca. 1800 mm)
• Mode shape: torsional mode of the carrier faces
Experimental modal analysis:> f = 236 Hz
Mode shape: torsional mode of the carrier faces • Resonance frequency: ∆f < 2,5 % (10 %)• Experimental results for structural damping
FE Model for elastic substructure: > f = 244 Hz
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IME/FVA Simulation tool DRESP
Example:
Rotor incl control structure1 Rotor incl. control structure1
4 Spur gear with 2 gear stages3 Planetary gear 2 Rotor shaft and rotor hub
4 Spur gear with 2 gear stages
6 Mass of generator incl. control structure for different load cases
5 Coupling and brake disk with controlstructure for braking torque
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structure for different load cases
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SIMPACK model of a full wind turbine (focus on gear box)
Rotor and (flexible) rotor shaft
SIMPACK model:
Planetary gear Spur wheel section Elastic coupling and brake diskElastic coupling and brake disk Generator (flexible) Machine support
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L d Moment Orbits
Simulation of wind turbinesBearing models for the simulation
linear
Loads Moment Orbits
no clearance
linear
non-linear
Rad
ial f
orce
[N]
-90000
-30000
30000
90000
150000
non linear
-150000
Radial deformation [mm]-0.080 -0.060 -0.040 -0.020 0.000 0.020 0.040 0.060 0.080
non-linear
BEARINX®
L S S h ffl KG Si l ti Wi d i l ATK 2009
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Lenssen, S., Schaeffler KG Simulation von Windenergieanalagen, ATK 2009
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Including the wind turbine control
In order to get a realistic operating performance, the logic control operations of the windturbine manufacturer are implemented.
Regulated variables for Power-control and control of the rotational-speed are Pitch angle
G t t Generator torque Braking torque
Most important variables which influence the procedures are: Windspeed and –direction (Yawing) Current rotational speed of the wind turbine Stored operating control for different operating and emergency situations
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Simulation results: Overview Run UP & validation
Generator Speed, measured / simulatedOmGen[rpm]
3D Wind field 3D Wind field Controller:
start-up process Pitch anglePitch angle Generator power control Aerodynamic power control
Feedback n(t), M(t), P(t)
Comparison between IME Aeroelastik@SIMPACK and Flex5 (rotational speed of the rotor)
Feedback n(t), M(t), P(t)
Aeroelastic rotors in Multibody Simulation
Comparison between IME Aeroelastik@SIMPACK and Flex5 (rotational speed of the rotor)
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Simulation results part A: WEA Run UP
• pitch
Beginning of synchronization generator to grid
• wind speed• rotor speed
Simulated time curves: pitch angle, wind speed, rotation speed of the rotor
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Simulation results part B: WEA Run UP
Beginning of synchronization generator to grid
• generator speedg p• electrical power• aerodynamic torque
Simulated time curves (aerodynamic rotor torque, rotational speed of the generator (actual/set),electric performace)
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Simulation results
Simulation results match with the given measurement data of a Multi-Mega-Watt-wind turbine.
Torsional moment in the rotor-shaft in stationary operation
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Summarycurrent activities at the IME
Summery Aeroelastic rotor modelling
Good fit with results to reference tools used by wind turbine manufacturers (Flex5, Bladed)Good fit with results to reference tools used by wind turbine manufacturers (Flex5, Bladed) Feedback on the transmission can be analysed in detail IME is also using the Aerodyn Code @ Simpack Aero Module
Model validation In current bilateral projects:
• Validation on component level (modal analysis)Validation on component level (modal analysis)• Test rig measurements (gearbox teeth excitation)• Flex5 calculations are taken as reference• Measurements on the wind turbine itself (statistical comparision)Measurements on the wind turbine itself (statistical comparision)
FVA 96/XVII: Research project „Modellfindung“
FutureHDTC IME/RWTH 1MW I li t t i d t t t th d f 2010 HDTC IME/RWTH: 1MW Inline test rig, ready to operate at the end of 2010
Planed: nacelle system testing at HDTC (turbine size as V52 or G52) Enhanced aerodynamics & aeroelastics for future wind turbine aspects
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Forecast: IME HDTC - Heavy Drive Train Center at RWTH Aachen Campus
• 1 MW In-Line testing station:
• System testing for WEA Nacelle y g• 1) Conected direct to fixed grid
• 2) Real time Grid simulation onpower level
• Start of Operation end of 2010
Stolle Span A = 14 m x 8 m M = 800 to air suspension
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