Integrating HyperWorks into the Development and Optimisation of Wind Turbine Rotor Blades

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Integrating HyperWorks into the Development and Optimisation of Wind Turbine Rotor Blades

  1. 1. Approved Center of Engineering, Technology and In Service Support Integrating HyperWorks into the Development and Optimisation of Wind Turbine Rotor Blades Dr. Christoph Katzenschwanz; Wolfgang KurzThe reproduction and distribution of this document as well as the communication of its contents to others without explicit authorisation by ACENTISS GmbH are prohibited.Offenders will be held liable for the payment of damagesEHTC 2011; ACENTISS GmbH © ACENTISS 2011 2.1-1
  2. 2. Agenda Presentation of ACENTISS and A2Wind Design Process of Rotor Blades Loading Constraints Optimisation Disciplines Macros to support the optimisation process Example Conclusion and OutlookEHTC 2011; ACENTISS GmbH © ACENTISS 2011 2
  3. 3. Presentation ACENTISS / A2Wind Approved Center of Engineering, Technology and Automotive InfoCom Transport & In Service Support Environment • ACENTISS as 100% GmbH of IABG Aeronautics Space Defence & • up to 30 employees end of Security 2011 Do328 Prop / Jet A318 – A321 A400M AEOLUS II Fuselage Sections Cargo Door Do728 A300,A330/340 B787 Aft Pressure Bulkhead MON 50 Airframe Primary A380 Pax / F LJ85 Structure System Integration Airframe Primary Structure Eurofighter Typhoon Fuselage Sections Avionic Design & Wing Components Subsystems Development Floor GridEHTC 2011; ACENTISS GmbH © ACENTISS 2011 3
  4. 4. ACENTISS Services & Engagements formed as a business company from two established companies specialized in design and development of wind energy systems experienced in developing turbines up to 3 MW rated power, including the complete design of rotor bladesEHTC 2011; ACENTISS GmbH © ACENTISS 2011 4
  5. 5. Agenda Presentation of ACENTISS and A2Wind Design Process of Rotor Blades Loading Constraints Optimisation Disciplines Macros to support the optimisation process Example Conclusion and OutlookEHTC 2011; ACENTISS GmbH © ACENTISS 2011 5
  6. 6. Design Process In-house tool aerodynamic ce ge r an om ol a mi , rm na etry et cp rfo ry ro om pe ae ge dy FOCUS 6 Optistruct loads loads structure mass, stiffness Structure, aerodynamic and loads are highly coupled An iterative process is needed to account for the interaction Objective of the design process should be revenue / costs but weight is used quite oftenEHTC 2011; ACENTISS GmbH © ACENTISS 2011 6
  7. 7. Typical Components of Rotor Blades upper flange upper skin web of front spar lower skin web of read spar (torsional moment) (shear forces) lower flange (bending moments)EHTC 2011; ACENTISS GmbH © ACENTISS 2011 7
  8. 8. Constraint: Tip Deflection Due to the aerodynamic and mass forces the rotor blade will be deformed The rotor blade needs sufficient bending stiffness to avoid a collision with the tower From the certification specification a stiffness requirement a ≥ 0.3 b has to be shownEHTC 2011; ACENTISS GmbH © ACENTISS 2011 8
  9. 9. Constraint: Modal Requirements for Rotor Blades Example of a Campbell Diagram for a Wind Energy Converter 4.0 Operational Range 3.5 3.0 1st Tower Bending Natural Frequency [Hz] 2.5 1st Rotor Blade Flapwise 1st Rotor Blade Edgewise 2nd Rotor Blade Flapwise 2.0 1st harmonic excitation 2nd harmonic excitation 1.5 3rd harmonic excitation 4th harmonic excitation 6th harmonic excitation 1.0 0.5 0.0 Resonance 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 Rotor Speed [Hz] flatwise edgewiseEHTC 2011; ACENTISS GmbH © ACENTISS 2011 9
  10. 10. Constraint: Strain Level The allowable strain values (tension and compression) of the fibres and the inter fibre failure has to be regarded tension compression For fatigue a simplified strain level can be used when no detailed fatigue calculation will be usedEHTC 2011; ACENTISS GmbH © ACENTISS 2011 10
  11. 11. Constraint: Buckling Due to compression or shear loads struts, plates etc. tend to fail Large displacements will occur and the aerodynamic is distorted Structural integrity is endangered A sufficient large buckling factor has to be shownEHTC 2011; ACENTISS GmbH © ACENTISS 2011 11
  12. 12. Constraint: Manufacturing Rotor blades are typically manufactured from the main substructures upper skin with flange lower skin with flange and web(s) For the flanges, leading and trailing edge typically a constant width of the fabrics is used For the layup of the fibres Bi- and Triax-fabrics are used (only 0° ±45°and , 90°fibre angles) Sandwich material is used Source: SGL-Rotec for the web and the skin (e.g. balsa, foam)EHTC 2011; ACENTISS GmbH © ACENTISS 2011 12
  13. 13. Agenda Presentation of ACENTISS and A2Wind Design Process of Rotor Blades Loading Constraints Optimisation Disciplines Macros to support the optimisation process Example Conclusion and OutlookEHTC 2011; ACENTISS GmbH © ACENTISS 2011 13
  14. 14. Optimisation Discipline Optistruct knows different optimisation disciplines like topology shape parameter/sizing. For the rotor blade only the sizing optimisation can be used because the outer loft is fixed for aero dynamical reasons In earlier optimisations the free size optimisation was used Each thickness of the plies in each element in the finite element model is variable through a design variable Optimal strength and stiffness distribution will be found Structure is manufacturable only at high costs The result of the optimisation has to be modified in a way that the manufacturing constraints can be regardedEHTC 2011; ACENTISS GmbH © ACENTISS 2011 14
  15. 15. Comparison Free Size - Sizing Optimisation Free Size Optimisation Sizing Optimisation + Maximum design flexibility ± Number of design variables less than free size optimisation + Easy to define design variables using − Design variables and the connection to the gauge function in HyperMesh the ply thickness has to be done by hand (The gauge function in HyperMesh does not help due to different min and max values) + Buckling load cases tend to high + Integrating buckling load cases into the numbers of iteration design optimisation is more stable − After the optimisation the + The optimised design is directly manufacturing constraints have to manufacturable introduced in further optimisations Combining the advantages of both strategies would be bestEHTC 2011; ACENTISS GmbH © ACENTISS 2011 15
  16. 16. Macro for the Design Variable - Requirements The width of the flanges, leading and trailing edge should be easily adapted using TCL macros The flange etc. has to be divided into several properties along the blade length The design variables are the thicknesses of the individual plies Individual min and max thickness per ply can be applied The stacking sequence is ignored using the SMEAR or SMCORE option on the PCOMP(G) cardsEHTC 2011; ACENTISS GmbH © ACENTISS 2011 16
  17. 17. Macro for the Design Variable - Implementation Several TCL-macros have been developed to support the optimisation process: macro to change the width of the flange, leading and trailing edge macro to split the rotor blade in longitudinal direction into different properties and define the design variables macros to define the constraints and optimisation parameters and a macro to support an efficient post processing of the resultsEHTC 2011; ACENTISS GmbH © ACENTISS 2011 17
  18. 18. Agenda Presentation of ACENTISS and A2Wind Design Process of Rotor Blades Loading Constraints Optimisation Disciplines Macros to support the optimisation process Example Conclusion and OutlookEHTC 2011; ACENTISS GmbH © ACENTISS 2011 18
  19. 19. Results - Optimisation History of a GFRP Rotor Blade 1.2 1.0 normalised response [-] 0.8 0.6 0.4 Total Mass 1st mod freq 0.2 2nd mod freq Tip disp 0.0 0 5 10 15 20 25 30 35 40 Iteration [-] blade length ~ 40 mEHTC 2011; ACENTISS GmbH © ACENTISS 2011 19
  20. 20. Result - Thickness Variation of Upper Flange ° Manufacturing constraint of constant width of flange, leading and trailing edge is regardedEHTC 2011; ACENTISS GmbH © ACENTISS 2011 20
  21. 21. Result – Thickness of Plies From the optimisation a thickness distribution is found which is then processed as ply based laminate property PCOMPP Element sets can be generated using EXCEL and a FORTRAN program Design guidelines are considered in a semi automatic process 30.0 12.0 Flange; SS-UD Flange; PS-UD 25.0 Flange; SS-Biax 10.0 Flange; PS-Biax 20.0 8.0 Thickness Biax [mm] Thickness UD [mm] 15.0 6.0 10.0 4.0 5.0 2.0 0.0 0.0 0 5000 10000 15000 20000 25000 30000 35000 40000 45000 Length [mm]EHTC 2011; ACENTISS GmbH © ACENTISS 2011 21
  22. 22. Objective Function Beside the objective minimum weight the target could also be minimum cost when a cost function is included A cost function is needed especially when different materials are combined E.g. combining glass 160 160 fibre reinforced plastic GFRP (GFRP) with carbon 140 140 CFRP fibre reinforced 120 120 material (CFRP) Material costs [%] Structural mass [%] 100 100 159 80 80 134 25 67 60 60 88 102 35 40 40 Cost estimation depends 57 55 on the blade and the 20 20 33 25 manufacturing process 12 0 0 These results can not be taken as general guideline GFRP/CFRP GFRP CFRP cost optimal flangesEHTC 2011; ACENTISS GmbH © ACENTISS 2011 22
  23. 23. Agenda Presentation of ACENTISS and A2Wind Design Process of Rotor Blades Loading Constraints Optimisation Disciplines Macros to support the optimisation process Example Conclusion and OutlookEHTC 2011; ACENTISS GmbH © ACENTISS 2011 23
  24. 24. Conclusion TCL-macros for the definition of the optimisation task help to reduce the time for the setup, to increase the reliability of the process and the optimisation know how is able to be used by all involved persons. Due to the shorter set up time for the optimisation more design variants can be analysed in the same time, design decisions are based on a fundamental analysis/optimisation rather than instinct and customers get lightweight rotor blades.EHTC 2011; ACENTISS GmbH © ACENTISS 2011 24
  25. 25. Outlook Further development will be done to integrate all the tools within a user panel / browser Setup model and design variables Define constraints and optimisation parameters Support of postprocessingEHTC 2011; ACENTISS GmbH © ACENTISS 2011 25
  26. 26. Thank you for your attention ACENTISS GmbH A2Wind GmbH Dr. Christoph Katzenschwanz Wolfgang Kurz Research & Technology, Innovations Technical Manager Wind Energy Einsteinstrasse 28a Einsteinstrasse 28a 85521 Ottobrunn 85521 Ottobrunn Germany Germany E-Mail Katzenschwanz@acentiss.de E-Mail w.kurz@a2wind.net Web www.acentiss.de Web www.a2wind.netEHTC 2011; ACENTISS GmbH © ACENTISS 2011 26

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