Preface

The HAWC2 code is a code intended for calculating wind turbine response in time domain. It has been developed within the years 2003-2006 at the aeroelastic design research programme at Risoe, National laboratory Denmark.

The structural part of the code is based on a multibody formulation where each body is an assembly of Timoshenko beam elements. The formulation is general which means that quite complex structures can be handled and arbitrary large rotations of the bodies can be handled. The turbine is modeled by an assembly of bodies connected with constraint equations, where a constraint could be a rigid coupling, a bearing, a prescribed fixed bearing angle etc. The aerodynamic part of the code is based on the blade element momentum theory, but extended from the classic approach to handle dynamic inflow, dynamic stall, skew inflow, shear effects on the induction and effects from large deflections. Several turbulence formats can be used. Control of the turbine is performed through one or more DLL’s (Dynamic Link Library). The format for these DLL’s is also very general, which means that any possible output sensor normally used for data file output can also be used as a sensor to the DLL. This allows the same DLL format to be used whether a control of a bearing angle, an external force or moment is placed on the structure. The code has internally at Risoe been tested against the older validated code HAWC, the CFD code Ellipsys and numerous measurements. Further on detailed verification is performed in the IEA annex 23 and annex 30 research project regarding offshore application. Scientific papers involving the HAWC2 is normally posted on the www.hawc2.dk homepage, where the code, manual and more can be downloaded. During the programming of the code a lot of focus has been put in the input checking so hopefully meaningful error messages are written to the screen in case of lacking or obvious erroneous inputs. However since the code is still constantly improved we appreciate feedback from the users – both good and bad critics are welcome. The manual is also constantly updated and improved, but should at the moment cover the description of available input commands.