During the last decades the annual energy produced by wind turbines has increased
dramatically and wind turbines are now available in the 5MW range.
Turbines in this range are constantly being developed and it is also being investigated
whether turbines as large as 10-20MW are feasible. The design of
very large machines introduces new problems in the practical design, and optimization
tools are necessary. These must combine the dynamic eects of both
aerodynamics and structure in an integrated optimization environment. This is
referred to as aeroelastic optimization.
The Ris DTU optimization software HAWTOPT has been used in this project.
The quasi-steady aerodynamic module have been improved with a corrected
blade element momentum method. A structure module has also been developed
which lays out the blade structural properties. This is done in a simplied way
allowing fast conceptual design studies and with focus on the overall properties
relevant for the aeroelastic properties. Aeroelastic simulations in the time domain
were carried out using the aeroelastic code HAWC2. With these modules
coupled to HAWTOPT, optimizations have been made. In parallel with the
developments of the mentioned numerical modules, focus has been on analysis
and a fundamental understanding of the key parameters in wind turbine design.
This has resulted in insight and an eective design methodology is presented.
Using the optimization environment a 5MW wind turbine rotor has been optimized
for reduced fatigue loads due to
apwise bending moments. Among other
things this has indicated that airfoils for wind turbine blades should have a high
lift coecient. The design methodology proved to be stable and a help in the
otherwise challenging task of numerical aeroelastic optimization.
- Aeroelastic design methods