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Drive Train DLL Options

Users with a licence for the Advanced Transmission Interface module may run Bladed simulations with user-defined gearbox dynamics provided in a Windows Dynamic Link Library (DLL). Bladed provides 2 gearbox DLL interfaces: the 1 Degree of Freedom (DoF) DLL interface where the gearbox dynamics include a single torsional DoF, and the 6 DoF DLL interface where the gearbox Low-Speed Shaft (LSS) dynamics have 6 DoF. The High-Speed Shaft (HSS) and generator rotor (mechanical) dynamics must be included in the 6 DoF gearbox DLL. Some simple example DLL source codes files written in Fortran and C++ are provided in the Code Samples folder of your Bladed installation.

Similar to other DLL interface the dynamic equations of motion are specified in continuous time state-space form.

For the DLL interface, all variables obey the GL sign convention, for example the low-speed shaft rotation is positive for a clockwise rotor. A negative gearbox ratio means that the high-speed shaft rotates in the opposite direction to the low-speed shaft. The low-speed shaft torque is the torque exerted by the low-speed shaft spring onto the gearbox input shaft. The high-speed shaft torque is the torque exerted by the gearbox output shaft onto the high-speed shaft spring (if the DLL represents just the gearbox) or by the generator rotor onto the generator stator (if the DLL represents the gearbox, high-speed shaft and generator rotor inertia).

The DLL may be written in any language which can be compiled to a Windows DLL. The 1 DoF DLL entry point from Bladed is a single procedure called DLL_GBX (upper case) and the 6 DoF DLL entry point procedure is called DLL_GBX_6DOF. Both procedures have eight arguments and no return value. Either the "__cdecl" or the "__stdcall" calling convention may be used.

In previous versions of the 6 DoF gearbox DLL interface, the DLL entry point procedure was called DLL_GBX. This interface is no longer supported; an error message will be issued and the simulation terminated on starting a simulation of a Bladed model which has an obsolete 6 DoF gearbox DLL.

It should be noted that the Data Group named External Gearbox DLL is only output when Drive train information is selected as a Calculation Output (see Other outputs tab).

External DLL for Transmission Dynamics

Select the External DLL checkbox to indicate that a user-defined DLL will be used to define the gearbox dynamics. The user then needs to select from one of the following three options to define the scope of the user-defined DLL:

  • Gearbox only - THis is a 1DOF DLL interface. The DLL replaces the gearbox in the Bladed model and has a single torsional degree of freedom only. Both the low and high-speed shafts in the Bladed model must have torsional flexibility defined. If the shaft brake is defined then it is also considered to be within the scope of the DLL. Note that this affects not only the braking torque but also the mechanical losses. Any flexible gearbox mountings must be modelled within the DLL if required.

  • Gearbox + HSS + generator rotor: the DLL replaces the gearbox ratio, high-speed shaft and generator inertia in the Bladed model and has a single torsional degree of freedom only. The low-speed shaft in the Bladed model must have torsional flexibility defined. If the shaft brake is defined then it is also considered to be within the scope of the DLL. Note that this affects not only the braking torque but also the mechanical losses. The slipping clutch model is not available in this case. But can be modelled within the DLL if required. Any flexible gearbox mountings must be modelled within the DLL if required.

  • Gearbox + HSS + generator rotor (6 DOF): the DLL replaces the gearbox, high-speed shaft, generator mass and inertia in the Bladed model and has full six degrees of freedom. The low-speed shaft and gearbox mountings in the Bladed model also have six degrees of flexibility defined. If the shaft brake is defined then it is also considered to be within the scope of the DLL. Note that this affects not only the braking torque braking torque but also the mechanical losses. The slipping clutch model is not available in this case. But can be modelled within the DLL if required.

Last updated 28-08-2024