Short description

FARM-WT is a numerical simulation tool devoted to preliminary design of wind turbine rotors through advanced, accurate and cost-effective modeling. The proposed technology focuses on blade aerodynamics and aeroelasticity. It can also be coupled to suitable aeroacustic models to evaluate wind turbine noise. Aim of FARM-WT is to help wind turbine community in the assessment of current designs, in the development of new concepts and in the maximization and control of power output capabilities. CNR-INSEAN has developed a devoted in-house aerodynamics and aeroelastic numerical tool that can be suitably positioned amongst the current literature on the subject. FARM-WT is a FEM-based software that can be used for blades design as well as to identify regulation strategies to optimize turbine power production for given wind profiles. It is based on a nonlinear beam-like blade structural dynamics formulation coupled with suitable 2D/3D Reduced Order Aerodynamics Models. 

Blade aerodynamic loads are evaluated through an unsteady aerodynamics load model. Specifically, the Beddoes-Leishman state-space dynamic stall model is enhanced by three-dimensional wake inflow to take into account rotor wake inflow influence on downwash. A free-wake Boundary Element Method (BEM) for unsteady attached, potential flows around lifting bodies is used to evaluate the wake inflow for different operating conditions. Widely used semi-empirical approaches to extend sectional steady aerodynamic  coefficients to high angles of attack and to model rotating flow effects are also considered to characterize wind turbine operations  in deep stall regimes.

The aerodynamic model is coupled with a nonlinear, integro-differential formulation governing structural dynamics of bending-torsional blades subject to moderate deformations. The formulation is general and can be extended to include the presence of the tower and floating structures for offshore applications. The level of accuracy in the physical description of the fluid-structure interaction makes the proposed approach among those having a leading position in wind turbine aeroelastic simulations. The theoretical modelling is applicable to turbines with non-uniform rotor blades, described as long, straight, slender, homogeneous isotropic beams undergoing axial, lag, flap and torsion displacements. The theory is intended for moderate displacements, is accurate to second order and may be enhanced to face advanced-shape blades.

This numerical tool can be also used to simulate a wind turbine rotor under yawed flow conditions and/or working within a significant vertical shear layer. Moreover, its mathematical formulation and its reduced computational costs make it particularly suitable for aero-servo-elastic applications such as blade pitch control for the optimization of energy production and loads minimization.

The proposed technologies are considered at TRL 3/4.

REFERENCES
1. Greco L, Testa C, Salvatore F. Design oriented aerodynamic modelling of wind turbine performances, Journal of Physics: Conference Series, 75, 2007.
2. Calabretta A, Testa C, Greco L, Gennaretti M. Assessment of a FEM-based Formulation for Horizontal Axis Wind Turbine Rotors Aeroelasticity,  Applied Mechanics and Materials, 798, 2015.
3. Calabretta A, Molica Colella M, Greco L, Gennaretti M, Assessment of a comprehensive aeroelastic tool for horizontal-axis wind turbine rotor analysis, Wind Energy, 2016.
4. Greco L, Muscari R, Testa C, Di Mascio A. Marine propellers performance and flow-field features prediction by a free-wake panel method. Journal of Hydrodynamics, Ser. B, 6, 2014.

Main technical features

• 3D unsteady aerodynamics modeling through a Boundary Element Method
• 2D unsteady aerodynamics modeling through Beddoes-Leishman dynamic stall formulation
• Enhanced aerodynamics modeling by coupling 2D and 3D models
• Deep stall and high angle of attack regimes modeled through semi-empirical models
• Blade structural modeling based on a Finite Element Method (FEM) approach
• Strong aeroelastic coupling between blade aerodynamics and structural dynamics

Type of partner sought

Tasks to be performed by the partner you are looking for.

Cross validation of FARM-WT with respect to other numerical tools and experimental data.
Use of FARM-WT for turbine blade design, review and optimization.
Developmente of the code to bring it to the market (code efficiency enhancement, generation of Graphical User Interface, etc.)