Search found 4861 matches

by Jason.Jonkman
Thu Dec 24, 2009 2:22 pm
Forum: Computer-Aided Engineering Software Tools
Topic: How to add new nodes to the blades?
Replies: 5
Views: 2491

Re: How to add new nodes to the blades?

Dear Mahdi, As I said in my prior post, the number and location of the structural sections in FAST-generated ADAMS models is determined by inputs BldNodes, RNodes, and DRNodes in the AeroDyn input file. If you want your ADAMS model to have more than 17 sections, increase BldNodes to be more than 17,...
by Jason.Jonkman
Wed Dec 23, 2009 10:14 am
Forum: Computer-Aided Engineering Software Tools
Topic: How to add new nodes to the blades?
Replies: 5
Views: 2491

Re: How to add new nodes to the blades?

Dear Mahdi Norouzi, The aerodynamic and structural discretization of a blade in FAST, AeroDyn, and FAST-generated ADAMS models is defined by the discretization specified in the AeroDyn input file. See inputs BldNodes, RNodes, and DRNodes in the AeroDyn input file, which are described in the AeroDyn ...
by Jason.Jonkman
Wed Dec 09, 2009 4:47 pm
Forum: Computer-Aided Engineering Software Tools
Topic: FlpStff and EdgStff
Replies: 3
Views: 2918

Re: FlpStff and EdgStff

Dear Andreas, In the NREL 5-MW baseline wind turbine report you refer to (http://www.nrel.gov/docs/fy09osti/38060.pdf), the structural twist is specified in Table 2-1 and the aerodynamic twist is specified in Table 3-1. The structural twist gives the orientation of one of the local principal elastic...
by Jason.Jonkman
Mon Dec 07, 2009 10:07 pm
Forum: Computer-Aided Engineering Software Tools
Topic: FlpStff and EdgStff
Replies: 3
Views: 2918

Re: FlpStff and EdgStff

Dear Andreas, The flapwise stiffness and edgewise stiffness are defined about the principal elastic axes of a cross section. The principal elastic axes need not be parallel and perpendicular with the chordline, although they are often quite close to this in practice. The flapwise stiffness and edgew...
by Jason.Jonkman
Mon Dec 07, 2009 9:49 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Results comparison FAST and Bladed
Replies: 19
Views: 15479

Re: Results comparison FAST and Bladed

Dear Yinping Yang, I cannot comment much on your questions because I don't know anything about your turbine, controller, or protection system. Many systems are OK with short and slight overloadings of the generator. But you should ask the developer of your controller why the controller permits overl...
by Jason.Jonkman
Mon Nov 30, 2009 12:43 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Results comparison FAST and Bladed
Replies: 19
Views: 15479

Re: Results comparison FAST and Bladed

Hi Yinping Yang, I didn't mean the min/max blade-pitch angles. I meant the initial blade-pitch angles (at time zero). Regardless of whether or not FAST is configured to use GH Bladed-style DLL controllers, the intial rotor speed and initial blade-pitch angles in FAST are specified within FAST's prim...
by Jason.Jonkman
Mon Nov 30, 2009 12:20 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Wind & Wave data
Replies: 64
Views: 28995

Re: Wind & Wave data

Hi Linhao Wu, The wind and wave data files used in the paper you referred to are not available on our website. This is because (1) the wave data is computed within our simulations (that is, it is not stored independently) and (2) many wind data files are needed to cover the range of inflow condition...
by Jason.Jonkman
Wed Nov 25, 2009 2:02 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Results comparison FAST and Bladed
Replies: 19
Views: 15479

Re: Results comparison FAST and Bladed

Dear Yinping Yang, Are you saying that all of the intial conditions for the structural states are the same between FAST and GH Bladed? What about the controller states, such as blade pitch angle? Regardless, the start-up transients may differ between the codes, depending on the differences in theory...
by Jason.Jonkman
Tue Nov 24, 2009 12:08 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Results comparison FAST and Bladed
Replies: 19
Views: 15479

Re: Results comparison FAST and Bladed

Dear Yinping Yang, The variation in the FAST output for the first 20 s of your simulation is likely related to the specification of initial conditions that are not close to the steady-state solution. Are you setting the same initial conditions in the FAST and GH Bladed codes? The aero-elastic theori...
by Jason.Jonkman
Tue Nov 24, 2009 11:47 am
Forum: Computer-Aided Engineering Software Tools
Topic: Tower fore-aft modes shapes
Replies: 12
Views: 9869

Re: Tower fore-aft modes shapes

Dear Yinping Yang, I asked Gunjit Bir about the tower-top properties from Test03_tower.bmi. He told me that the inputs were not chosen to match the true tower-top properties of the WindPACT 1.5-MW turbine; instead, they were chosen simply as an example. If you want to model the WindPACT 1.5-MW turbi...
by Jason.Jonkman
Mon Nov 23, 2009 12:29 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Tower fore-aft modes shapes
Replies: 12
Views: 9869

Re: Tower fore-aft modes shapes

Dear Yinping Yang, The equations you stated for cm_loc and cm_axial are correct. As I said in my prior post, I do not believe that the tower-top mass input data are specified correctly for the WindPACT 1.5-MW turbine in Test03_tower.bmi of the BModes CertTest. I need to ask Gunjit Bir about this. Yo...
by Jason.Jonkman
Fri Nov 20, 2009 6:08 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Tower fore-aft modes shapes
Replies: 12
Views: 9869

Re: Tower fore-aft modes shapes

Dear Yinping Yang, Your understanding of tip_mass in BModes is correct. cm_loc in BModes is the horizontal offset along the xt-axis from the tower centerline to the center of mass of tip_mass. cm_axial is the vertical offset along the zt-axis from the tower top/yaw bearing to the center of mass of t...
by Jason.Jonkman
Tue Nov 17, 2009 2:07 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Tower fore-aft modes shapes
Replies: 12
Views: 9869

Re: Tower fore-aft modes shapes

Dear Yinping Yang, I agree with how you incorporated the point masses into the mass distribution and I agree that you should not change the stiffness distribution. From my experience, the frequencies that the Modes code calculates are far more accurate than the mode shapes that the Modes code calcul...
by Jason.Jonkman
Fri Nov 13, 2009 9:11 am
Forum: Computer-Aided Engineering Software Tools
Topic: Nacelle Yaw Parameter (YawSpr and YawDamp)
Replies: 3
Views: 2017

Re: Nacelle Yaw Parameter (YawSpr and YawDamp)

Hi Yinping Yang, The yaw bearing mass is often lumped into the mass of the nacelle. This is how all of the models in the FAST CertTest were made. You can separate out the masses if you wish, but it will have no impact on the dynamic response because the nacelle is modelled as a rigid body in FAST (t...
by Jason.Jonkman
Wed Nov 11, 2009 9:20 am
Forum: Computer-Aided Engineering Software Tools
Topic: Nacelle Yaw Parameter (YawSpr and YawDamp)
Replies: 3
Views: 2017

Re: Nacelle Yaw Parameter (YawSpr and YawDamp)

Hi Yinping Yang, To model the nacelle-yaw bearing as a rigid joint, simply disable the yaw DOF (YawDOF = False). Otherwise, setting YawSpr to a very large number will introduce a very high natural frequency in the system model. High natural frequencies require small time steps to avoid numerical ins...

Go to advanced search