Science Meets Practice Innovations for Wind Energy HUSUM WindEnergy 11 September 2008 D. Schwab and A.P. Schaffarczyk (APS) CEwind and UAS (FH) Kiel
Measure Yaw Misalignment: New Methods and Models The Influence of Yawing Error on Performance of Wind Turbines
Contents Introduction CEwind Actuator Disk Models Measurements in Wind Tunnels Summary and Outlook
CEwind in a Nutshell 1. Period: 01.01.2005 31.12.2007 2. Period under Consideration : Eingetragene Forschungs-Genossenschaft (e.g.) Own legal form: Cooperative Society Budget about 1M /a Network of : University Kiel (Tech. Fak., FTZ Westküste), University Flensburg (Prof. Hohmeier, IPCC) all Universities of Appl. Sciences Nordakademie Elmshorn
Special Projects Mechanical Engineering 1. Period : 2. Period: 1. Offshore Windturbine Foundation Structural Design of Rotorblades (Prof. Dannenberg, FH Kiel) 2. Aerodynamics and Aeroelastics of Large Rotor-Blades (Prof. Schaffarczyk, FH Kiel) 3. Condition Monitoring (Prof. Krapoth / Prof. Reimers FH Flensburg) Aerodynamic Glove CM of Blades including Power Electronics (Prof. Fuchs, CAU)
Special Project: MSc Wind Engineering Starting NOW! Applications Welcome! Master-Thesis S3 Grid Integration And High Generator and Power Electr.. Control Systems and Automation Basics Environment Add. Courses like Add. Courses like S2 Noise & Vibration Structural Strength & Materials Aerodynamics Sustainable Energy Systems Shaping Sustainable Energy Systems Add. Courses like S1 1 CP Add. Courses like Advanced Windturbine Systems Off-Shore Mathematics Measurment and Certification External Costs of Energy Trading Energy 1 Modul = 5cp: Lectures Exercises Laboratory Course Power Train Components Emphasis Environment Business Economics Project Work
Offshore Measurement platform FINO 3 Construction in 2008 45 nm west of the island of Sylt measurements of wind and rainfall, tide and drift, interaction between foundation and ground, lightning parameters, Subproject: Measurement and analysis of high- frequency (<10 khz) turbulence parts in the offshore wind for optimization of aerodynamic profiles
Actuator Disk Modeling of Yawed flow (1) Yawed Flow: Wind NOT in Direction of Rotational Axis Main Questions: Which Loss in Power? What Changes in Loads? Disc = British Disk = American
AD Modeling of Yawed flow (2) Actuator Disk (Rankine, Froude, 19th Century) Rotor is modeled as infinitely thin solid disk no effects of finite number of blades included (Semi)-Analytical Method applicable: Solution of Axis-symmetric, inviscid Euler-Equations Mathematical formulation in terms of velocity potentials
AD Modeling of Yawed flow (3) Problem for applying momentum theory -> Axis Symmetry is lost! Improved AD Models (From Helicopter Applications): (1) Axial Momentum only (2) Glauert Momentum (1926) (3) Vortex Methods (Coleman et. al. 1945)
Results (1) Simplest Model (1) Circumferential Averaged Axial induction as function of yaw angle : Gives: cp(-max) of approx. 1 % loss for 5 deg yaw-angle *** Most used engineering formula *** (not talking about exponent 3 )
Results(2) Losses rather model-dependent if yaw angle becomes large: 10 Source: Wind Energy Handbook
New AD Model(1) Conway (2001) gives a non-linear semi-analytic AD theory for non-axi symmetric flow Special load distribution in form of polynomial Enthalpie-Streamfunction functions necessary This triggered a CFD test of the method Hub Tip
New AD-Method (2) Sketch of axial Flow-Field, 10 deg yaw, TSR = 6 Commercial CFD-Code FLUENT improved by User- Subroutines
New AD-Model(4) Total axial velocity
New AD-Method (3) Some difference can be seen Conway = light green
Yawed Flow Loads (1) Mikkelsen (2004), 30 deg yaw Flapwise root bending moment Dynamic stall important
NASA AMES (World Largest) Wind-Tunnel Power: 6 x 13.6 MW
2 bladed 10 m diameter Test-Turbine
Yawed Flow Loads(2) NREL-NASA-AMES Experiment (2000) Circumferential Normal Force against BEM modeling --Solid Line (meas.) Strong variation of Design-Codes -- thin lines (theory)
(European) Mexico Experiment (2001-2007) 3-bladed wind-turbine in Largest European wind-tunnel Diameter 4.5 m
IEA-Task for Evaluation of results I(nternational) E(nergy) A(gency) Special Task starts today (Therefore APS is absent) MEXNEX(T): Analysis of Wind Tunnel Measurements and improvement of aerodynamic models Also Yawed Flow was extensively measured
Summary Yawed Flow is unsteady 3D therefore modelling is full of simplification ongoing research(nrel/nasa-ames, MEXICO) important for turbine control optimization -> following presentation of ixist
The End many thanks for your attention!