Structural Optimization of Vertical-axis wind Turbine Composite Blades Based on Finite Element Analysis and Genetic Algorithm

Significance Statement

Installing offshore wind farm can be challenging. Horizontal-axis wind turbines (HAWTs) have maintenance difficulty due to the location of its rotor and drive-train which are to be installed at the top of very tall towers. To improve the use of wind turbine, vertical-axis wind turbines (VAWTs) were introduced which overcame the disadvantages of HAWTs by locating their main components at the base of the wind turbine and made both installation and maintenance easier. It is possible to further improve the performance of wind turbine by optimizing the blades of the wind turbine. Wind turbine blades are made of composite materials due to their high strength-to-weight ratio and good fatigue performance. Additionally, wind turbine blades generally have complex structural layout including one or more shear webs and a number of composite plies placed at different ply angles, making their structural design quite challenging.

Dr. Lin Wang and colleagues from Cranfield University in the UK combined finite element analysis (FEA) and genetic algorithm (GA) to develop a structural optimization model of wind turbine composite blades. The research work is now published in peer-reviewed journal, Composite Structures.

The research team categorized the structural models used for wind turbine blades into two groups, that is one dimensional (1D) beam model and three dimensional (3D) FEA model. Due to the complexity of wind turbine blades structural layout, the team suggested combining FEA and GA to develop a structural optimization model of wind turbine composite blades. They applied the structural optimization model to ELECTRA 30 kW wind turbine blade, which is a novel VAWT blade, to optimize the structural layout of the blades. The optimization model took into consideration stress constraint, deformation constraint, vibration constraint, buckling constraint, and manufacturing maneuverability and continuity of laminate layups constraint.

The optimal blade design leads to a mass reduction of 17.4% in comparison with the initial design, the maximum total deformation is about 0.593 m and observed at the tip of the upper sail. The deformation value obtained is 15.3% lower than the allowable value of 0.7 m, the shows the new blade design is quite stiff and is not likely to experience large deformations. The team pointed out that the blade will not suffer from buckling, due to its load multiplier being 2.15 that is 43.33% higher than the minimum allowable value of 1.5. From the stress distribution, the research team observed the maximum positive normal stress to be 151.72 MPa, which is 52.90% lower when compared with the allowable value of 322.1 MPa. And the maximum negative normal stress (i.e. maximum compressive stress) to be very close to the allowable value.

This study demonstrated that the structural optimization model presented is capable of improving the efficiency of blade structural optimization and effectively and accurately determining the optimal structural layups of composite blades.

Structural Optimization of Vertical-axis wind Turbine Composite Blades Based on Finite Element Analysis and Genetic Algorithm - renewable energy global innovations
Figure 1. NOVA 10MW wind turbine.

About the author

Dr Lin Wang is currently a Research Fellow in Structural Mechanics at Cranfield University. He received his BEng (Hones) degree in Mechanical Design and Manufacturing Automation and MSc degree in Mechanical Engineering from Xiangtan University in 2009 and 2011, respectively, and completed his PhD in Wind Energy Engineering from the University of Central Lancashire in the UK in 2014. Dr Wang has authored more than 20 peer-reviewed journal and conference papers, and acts as a reviewer for high-profile journals. Additionally, he has been involved in delivering lectures and tutorials for both undergraduate and postgraduate students.

About the author

Dr Athanasios Kolios (Dip Eng, MSc, PhD, MBA, PGCAP, CEng MIMechE, FHEA) is a Senior Lecturer in Risk Management and Reliability Engineering and Director of the Energy Doctoral Training Programme at Cranfield University. He has authored more than 60 peer-reviewed journal and conference papers, acts as a reviewer in key journals and has chaired sessions on the Risk and Integrity Management of Energy Assets. He is a member of the board of the European Academy of Wind Energy and a member of the ISSC Offshore Renewable Energy Committee. He currently leads the Risk and Reliability Engineering, Computer Simulations in Engineering Design and Renewable Energy Technologies for several MSc courses of the Energy Theme at Cranfield University. Dr Kolios is a Chartered Engineering of the Institution of Mechanical Engineers and a Fellow of the Higher Education Academy. He has supervised MSc and PhD students through to completion.

About the author

Dr Takafumi Nishino obtained his Bachelors and Masters degrees in Mechanical Engineering from Kyoto University in Japan in 2002 and 2004, respectively, and his PhD in Aerodynamics from the University of Southampton in the UK in 2007.After spending four months as a Visiting Researcher at AGH University of Science and Technology in Poland, he moved to NASA Ames Research Center in the US in 2008. He spent three years at NASA Ames for his postdoctoral research, which contributed to the Subsonic Fixed Wing (SFW) project in the Fundamental Aeronautics (FA) program at NASA. In 2011 he returned to the UK and joined the Tidal Energy Research Group at the University of Oxford as a Research Assistant. He spent three years in Oxford for his research and teaching (tutoring) mostly in hydrodynamic modelling of marine turbine arrays, prior to joining Cranfield University as a Lecturer in 2014.

About the author

Dr Pierre-Luc Delafin obtained his Bachelors and Masters degrees in Fluid Mechanics and Energetics from Grenoble Institute of Technology in France in 2008 and 2010 respectively, and his PhD in Fluid Mechanics and Energy from the University of Western Brittany (France) in 2014. During his PhD at the Naval Academy Research Insitute (France), his research was focused on the laminar to turbulent transition on hydrofoils through experiments and RANS and LES calculations as well as the hydrodynamic performance of a variable-pitch vertical-axis tidal turbine through RANS calculations. He was also involved in teaching activities in Computational Fluid Dynamics (CFD), Experimental Fluid Dynamics, thermodynamics and vibration. He joined Cranfield University in December 2014 as a Research Fellow in Aerodynamics and CFD to work on a novel vertical-axis wind turbine.

About the author

Mr Theodore Bird is the Founder of Aerogenerator Project Limited and has seeded the project with own funds and a Smart Award, and won a Shell Springboard Award and secured ETI project funding worth £3m, subsequently managed all funded projects. Currently he is leading a further developmental project, to build a small scale commercial VAWT through a DECC grant which will also stand as a validation platform for the numerical models that have been developed to scale up the concept.

Journal Reference

Lin Wang1, Athanasios Kolios1, Takafumi Nishino1, Pierre-Luc Delafin, Theodore Bird2, Structural optimization of vertical-axis wind turbine composite blades based on finite element analysis and genetic algorithm, Composite Structures 153 (2016) 123–138.

Show Affiliations
  1. Centre for Offshore Renewable Energy Engineering, School of Energy, Environment and Agrifood, Cranfield University, Cranfield MK43 0AL, UK.
  2. Aerogenerator Project Limited, Ballingdon Mill, Sudbury CO10 7EZ, UK.


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