One blade and multiple centre os pressure (ADAMS)

Hi,

I am modelling a three blade windturbine with ADAMS and AeroDyn. I have some problems during simulating my model. Each blade is divided in 5 blade elements and each blade element comes from a .mnf file from Patran Nastran software. Each element is made by solid elements from Patran. The problem is when I try to joint the elements. I have to define several Joints in the interface between the elements and this is problematic for ADAMS.

My question is: Is it possible to define only one blade element and several pressure centers? The idea is to use only one element for each blade (the entire blade) and within this element try to define 5 or more pressure points where to apply the aerodinamic forces.

Thanks in advance,

Alex

Dear Alex,

MSC.ADAMS has no problem if you create a PART that is loaded by multiple GFORCE loads. Please remember that if you are building your own ADAMS dataset by hand, and if you want to link this model with AeroDyn through the ADAMS2AD interface routines, you will have to follow all of the guidance documented in the ADAMS2AD User’s Guide: wind.nrel.gov/designcodes/simulators/adams2ad/. Is this what you are doing?

As an alternative, our FAST code has a preprocessor for creating ADAMS datasets of wind turbines for you: wind.nrel.gov/designcodes/simulators/fast/. This FAST-to-ADAMS preprocessor, as it is known, includes all of the AeroDyn-ADAMS interface specifications automatically. The current FAST-to-ADAMS preprocessor builds a blade in ADAMS using the same descritization for the aerodynamics and the structure, so, each PART will have only one GFORCE (we plan to allow for different aerodynamic and structural descritizations in a future release). However, 15 to 20 aerodynamic nodes per blade is much more appropriate than 5.

That said, if you plan to model the blade in ADAMS with only single PART, I question why you want to use ADAMS in the first place. ADAMS is meant for much more complicated models; it would be far easier to model the turbine using our FAST or YawDyn (wind.nrel.gov/designcodes/simulators/yawdyn/) codes.

Best regards,

Dear Jason,

thank you for your clear explanation.

The reason I would like to make the model with only one element blade per blade is that I am using ADAMS/Flex with diferent parts. These parts (tower, axis, blade elements,…) are coming from a .mnf file from Patran-Nastran software. The thing is that I have these parts meshed from Patran-Nastran with the flexible properties of the materials, real geometry,… When I make the joint between two element blades, for example, I have to joint several nodes (markers) in those meshes. The idea is to make the joint between the element blades in several points of the mesh (more realistic). When I check the model in ADAMS, there are some warnnings and errors. I could avoid these errors using only one element blade per blade (the entire blade) without several joints.

I have read the AeroDyn User´s Guide and I understand that I have to change the ID numbers of the Markers and take some rules in my ADAMS model. But that is not a problem (I think…).

The reason I try to use AeroDyn instead FAST is because I simulate the entire windturbine with the tower, axis and blades (all of them with the real geometry and real material proporties). I have made a previous model in ADAMS/Flex and I have applied some forces (forces values variables in time) to check the model and the model show me how are the vibrations of the tower and how are the level of stresses due to these variable forces. The idea is to use the interface with AeroDyn. That is the aim of using ADAMS/Flex. I do not know if using FAST I could get the same results…

Another question I have: the gyroscopic effect is implement in the ADAMS / AeroDyn interface? The windturbine I am working on it is a free yaw so the gyroscopic loads are very important and high. But I do not know if ADAMS / AeroDyn takes this into account…

I hope now my previous questions are more clear.

Thanks in advance,

Alex Estevez

Dear Alex,

The typically design approach is to use a full-system dynamics model–such as FAST with AeroDyn or ADAMS with AeroDyn–in order to model the coupled dynamics of the compete system, considering wind, aerodynamics, structural dynamics, and the controller. The outputs of these simulations are the loads (shear forces, bending moments, etc.) throughout the various components of the turbine, such as the blades, hub, drivetrain, and tower. These outputs are then used to feed FE-based models of individual components in order to determine the stress distributions.

Both FAST and ADAMS intrinsically include gyroscopic effects in their models of free-yaw wind turbines.

Best regards,

Hey Everyone, dear FAST-community

I working on designing a free yawing 10kW downwind wind turbine with 6m blade raius and a tower height of 20 meters. This turbine is supposed to be standing in a terrain with a lot of wind shear,high roughness…
For the free yawing performance of the turbine I would like to know more details about the implementation of the calculation of the yaw moments due to gyroscopic/coriolis forces in FAST.
Due to the complex and untypical turbine design, we unfortunatly cannot use FAST for our simulation.

Would it be possible to get to know the equations behind the calculation in FAST for the yaw movement?
Or is there any kind of documentation about the implementation?

Thanks everyone!

Best regards

Alexander Breitenbach

Dear Alexander,

Information on the theory basis of the structural model of FAST v7 and the ElastoDyn module of FAST v8 is provided in the following forum topic: http://forums.nrel.gov/t/coupled-blade-modes-in-fast/314/1.

Best regards,