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Table of Contents

Defining the Hub

From the Rotor screen, click the Hub tab to define the hub characteristics.

Enter the Spinner diameter. This is the diameter of any spinner or nose-cone, within which the blades themselves experience no aerodynamic forces.

Blade Root Section

The blade root section connects the blade root to the shaft. It is assumed to be cylindrical in section. It is defined by:

  • Length - This defines the actual radius of the first blade station. Set this to zero if there is no root section. The rotor diameter must be twice the sum of the root section length and the blade length, defined by the radial position of the last blade station.

  • Diameter - The diameter of the cylindrical tube which forms the blade root section.

  • Drag Coefficient- The drag coefficient to be used for any part of the blade root section which is outside the spinner. Zero lift coefficient is assumed.

If the spinner entirely covers the root section, the diameter and drag coefficient values will not be used.

Mass Information

For dynamic calculations, check the Mass checkbox to allow the necessary masses and inertias to be specified as follows:

  • Hub mass - The mass of the hub, including the spinner and any blade root section.

  • Hub mass centre - The distance from the intersection of the shaft and blade axes to the centre of mass of the hub, in direction measured away from the tower.

  • Moments of inertia - The moment of inertia of the hub mass about the shaft axis must be defined. The inertia about an axis perpendicular to the shaft may also be entered with its origin about the hub centre of mass.

If the Direct Drive option is selected, enter the moment of inertia of the generator rotor here.

For direct drive systems, enter also the generator mass information as follows:

  • Generator mass - Mass of the generator stator.

  • Generator mass centre - The distance between the centre of mass of the generator and the centre of mass of the hub.

  • Moments of inertia - The moment of inertia of the complete generator may be defined, about the shaft axis and a perpendicular axis.

In this case, ensure that the mass information entered on the nacelle screen does not include these contributions.

For one-bladed rotors only, define the counterweight as follows:

  • Mass - The mass of the counterweight.

  • Inertia about shaft - The moment of inertia of the counterweight about the shaft axis.

Note

The Turbine Information window shows the total masses and inertias of all turbine components whose mass characteristics are defined. Click Mass Totals, or use the Windows pull-down menu on the main toolbar to open this window.

Imbalances

Use the Calculation Parameters > Imbalances window to define any mass imbalance of the hub or rotor, or errors in the set angle or the pitch angle of one or more blades.

A mass imbalance can be added to the hub/rotor system. The user must specify the mass, radial and azimuthal position of the centre of gravity of the imbalance mass. An azimuthal position of zero would place the additional mass along blade 1. It is placed in the unconed rotor plane.

Note

The imbalance mass is an additional mass and therefore will affect the mass total and also the moment of inertia of the turbine.

  • Error in blade set angle - For each blade, specify the error in set angle. This will rotate both the pitching and non-pitching sections of the blade.

  • Error in pitch angle - For each blade, specify the error in pitch (or aileron/airbrake) angle. This will rotate only the sections of the blade that are outboard of the pitch bearing.

  • Error in blade azimuth - For each blade, specify the error in azimuthal position for each blade.

Last updated 28-08-2024