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HAWT Turbine

This sub-tab focuses on the Turbine in general terms. The following properties need to be defined :

General

  • Upwind or Downwind turbine*: radio buttons allow to choose one or the other. Upwind option allows you to model the rotor facing the wind, while with the downwind option, the rotor is located behind the tower.

Clockwise or anticlockwise rotation: radio buttons allow to choose one or the other.

Note

Blades pitch profile and twist profile are automatically updated as the wind turbine is switched from clockwise rotation to anti-clockwise rotation (or the opposite). A warning message displays as you change from clockwise rotation to anti-clockwise rotation asking whether you wish the blades pitch and twist profiles to be updated. Blades pitch and twist profiles has to be adapted manually when switching from clockwise rotation to anti-clockwise rotation in former versions.

Tower

  • Tower height (m) : From bottom of nacelle (slew ring) to sealevel. This is a read only field, its value is automatically computed.

Shaft

  • Tower to shaft (m) : Height from bottom of nacelle to shaft centreline/tower centreline intersection.

  • Overhang (m): Distance from hub centre to shaft centreline/tower centreline intersection.

  • Shaft tilt angle (deg) : The angle from horizontal of the shaft (assuming the nacelle is horizontal at t=0). Positive is nose down.

Hub

  • Hub radius (m) : Distance from the intersection of the blade and shaft centreline to the hub/blade root intersection.

  • Hub center of mass (HubCM) : position of hub centre of mass defined as usual.

Please note that in the current version, a change in the model in HubCM value in the Turbine sheet is properly taken into account only after opening the Hub and Fairlead/Hang-Off points sheet of the HAWT editor. It is advised to visually check that the shape of the first segments of you blade has been properly modified

Blades

  • Precone angle (deg) : The shaft tilt angle translates into a nominal blade departure angle from the hub, which has the precone angle subtracted from it. The precone angle is essential to ensure the blades are presented to the wind at an optimal angle, compensating for the shaft tilt angle. Note also that most blades have a pre-bend approaching the tip, as under load the blades will bend backwards towards the tower. This pre-bend also optimises the blade position under load and prevents clashing with the tower.

  • Tip radius : The blade radius from the centreline of the hub at the hub CM to the tip.

Nacelle

  • Nacelle center of mass coordinates (CM) : In this context the mass includes all the contents of the nacelle. Referenced from the shaft centreline/tower centreline intersection. It assumes a positive value is behind the shaft, as the nacelle mass normally balances the hub/blade mass as closely as possible around the main bearing.

Number of blades :

  • Simply set by entering a value or using the pull-down.