Drive Train Flexibility Options

When using the standard drive train modelling options in Bladed the user may incorporate flexibility into the drive shafts. For the low-speed shaft (LSS) both torsional flexibility and transverse bending of the shaft can be defined. For the high-speed shaft torsional flexibility can be defined. Select the Power Train > Transmission tab to view and edit the drive shaft flexibility options.

Low-Speed Shaft Flexibility

Use the check boxes to specify if there is Low-speed shaft torsional flexibility in the low-speed shaft. Supply the torsional LSS stiffness and LSS damping if flexibility is switched on. If both low and high-speed shafts are flexible it is necessary to define the gearbox inertia. The gearbox inertia is defined on the HSS side in the multibody structure.

Low-speed shaft bending can be modelled in Bladed with two rigid massless shafts connected at a hinged bending point. Enter the total LSS length and the bending point. The point of bending is entered as a percentage along the shaft length measured from the hub. For example, a bending point of 0% positions the hinge at the hub. By contrast a bending point of 100% positions the hinge flexibility is at the gearbox. The hinged connection is modelled as a 2D hinge, with freedoms 'y' and 'z' that are transverse to the shaft rotational 'x' axis. The transverse bending stiffness and damping of the hinged connection should also be entered.

Note

If not including flexibility in the high-speed shaft, gearbox or pallet mounting, the LSS stiffness parameter should reflect the total torsional flexibility between the rotor and the tower top. For most geared transmission configurations this will include the series combination of low-speed shaft flexibility and equivalent torsional flexibility of the gearbox mounting arrangement (if not defined separately in the Mounting screen) you should also consider whether the rotor hub, gearbox low-speed stage and/or yaw bearing roll present significant additional torsional flexibilities about the low-speed shaft axis.

High-Speed Shaft Flexibility

Use the check boxes to specify if there is High-speed shaft torsional flexibility in the high-speed shaft. Supply the torsional HSS stiffness and HSS damping if flexibility is switched on. If both low and high-speed shafts are flexible it is necessary to define the gearbox inertia. The gearbox inertia is defined on the HSS side in the multibody structure.

Last updated 28-08-2024