Specifications and features
HAWC2 is able to simulate wind turbines in time response with following properties:
- Normal onshore with 1,2, 3 or more blades
- Vertical Axis Wind Turbines (VAWT)
- Pitch and (active) stall controlled wind turbines
- Guyed support structures
- Offshore turbines on monopoles, tripods or jackets
- Floating turbines with mooring lines
- Multiple rotors in one simulation
- Multi-body formulation that can handle multiple degrees of freedom (like blade torsion)
- Structural beam element based on an anisotropic fully populated stiffness matrix (BECAS output data).
- Detailed aerodynamic BEM model that includes:
- Dynamic stall models: Stig Øye model, a modified Beddoes-leishmann model and a model for ATEF (Active Trailing Edge Flaps)
- Skew inflow model
- Shear effects on the induction
- Dynamic inflow model
- Near wake model
- Aerodynamic 2D actuator cylinder model for VAWT
- High fidelity aerodynamics by a SFI (structure-fluid interaction) coupling to the CFD code EllipSys3D
- Hydrodynamic model based on Morrison’s equation, WAMIT or McCamy & Fuchs.
- Water Kinematics that includes:
- Currents
- Linear airy waves
- Irregular airy waves
- Deterministic irregular waves
- Stream function wave
- Able to read pre-generated water kinematics
- Wind, turbulence and wake models:
- Able to read Mann turbulence model from the WAsP engineering
- Build-in Mann turbulence generator (Fully coherent 3D-turbulence)
- Able to read Veers turbulence model (used in FLEX5)
- Dynamic wake meandering model
- Default controller provided with a pitchregulated variable speed controller
- Coupling of external systems like Mooring lines, WAMIT etc.
- Soil module consisting of a set of spring-damper forces attached to a main body.
- Eigenvalue analysis at standstill
Development
First Generation: HAWC
The first generation of HAWC (Horizontal Axis Wind turbine Code) was initiated by J.T. Petersen in 1986 as a part of a PhD study. In 1993 it was chosen as the reference aeroelastic research model by Risø.
Second Generation: HAWC2
The second generation of the code, HAWC2 started development in 2003 where the core of the program was created in the following years. Further development of new submodels is still ongoing at the aeroelastic department at DTU Wind Energy. The code has been verified through measurements and comparisons with other codes. It has been used to simulate more than 100 different wind turbines. The HAWC2 has many significant features, particularly related to design and load simulation of large wind turbines in multi MW size. HAWC2 has also been extended for calculating on Vertical Axis Wind Turbines (VAWT).
HAWC2 parts and models
HAWC2 consists of models describing the external effect, applied loads, structural dynamics and connection to the control system. The external effects models how the wind, waves and soil is expected to behave. The applied loads models how the external effects interact with the structure through aerodynamic, hydrodynamic and soil models. The structural formulation of HAWC2 is based on a multi-body system. This enables a wide range of model capabilities and the possibility to include non-linear geometric effects. Wind turbine control is preformed through external DLL´s (Dynamic Link Library) that operates the system under different conditions.
Wind turbines are normally categorized using the IEC classification of I, II or III with turbulence levels classified between A and C. This is a very practical way of categorizing as it reduces the work of turbine approval. However, in some cases the site conditions are not fulfilled in all requirements for the classes which then require site-specific load simulations. One example could be high turbulence levels from a specific wind sector, significant wind shears, or turbulence effects from a neighbouring wind turbine. In these circumstances, the site requirements are not fulfilled, but the design loads on the turbine might still be unaffected, but however, have to be examined using an aeroelastic code. HAWC2 is a part of the commercially available codes from DTU Wind Energy, which also include the software programs HAWCStab2, BECAS, WAsP and WAsP Engineering. HAWCStab2 is a powerful tool for aero-servo-elastic design and tuning of controllers, and it uses the same input as HAWC2. BECAS is an Open-Source Cross Section Analysis Tool that can be used to calculate HAWC2 structural property input for advanced components like the blades. WAsP is used for wind resource assessment, and WAsP Engineering is used for site-specific wind conditions, which can be used as input for HAWC2.