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HAWT Power train

Inside the nacelle the relative positions of the generator and gearbox and their respective shafts and bearings are important to control loads and stresses.

This sub-tab allows the details of these items to be entered:

Low speed shaft (LSS):

The LS Shaft is automatically connected with a clamp to the Hub center and it follows the defined tilt angle. The following properties are required:

• Length

• Outside diameter

• Wall Thickness

• Lineic mass (mass per unit length)

• Axial stiffness

• Bending stiffness

• Torsional stiffness

• Young modulus of low speed shaft material

• Poisson coefficient of low speed shaft material

• Specific gravity of low speed shaft material

• Rayleigh structural damping coefficient of low speed shaft material

If the user gives the distance of this bearing from the rotor and the bearing length, two fairleads are created in the nacelle rigidbody, and a Pin-Pin connection made with two points on the shaft.

High speed shaft (HSS): (optional)

Click the check-box on if you wish to model this).

Same properties than for the LSShaft must be defined.

Main bearing:

The following properties are required.

• Linear position from rotor (along shaft, distance is from hub centre to main bearing centre).

• Bearing length

G earbox:

• Gearbox ratio: If there is an HSS the ratio determines the generator speed based on the rotor speed.

• Generator inertia (kg.m2)

• Gearbox efficiency: The gearbox efficiency is used to model power loss due to internal friction in the gearbox. Setting this value to 1 means that there is no power loss. The gearbox efficiency can be either constant or variable function of rotational speed or torque. The check box located next to the "User Table" button must be activated to define variable gearbox efficiency.

Clicking the 'use table' button brings a table where you can input the efficiency of the gearbox function of the rotational speed or function of the torque.