Search found 382 matches

by Marshall.Buhl
Wed Sep 24, 2014 4:19 pm
Forum: General
Topic: Retirement
Replies: 0
Views: 4373

Retirement

Hi, After working at NREL for 35 years, I have decided to retire and move back to my home state of Florida. My last day at the lab will be September 30, 2014. I will not be a regular contributor to these forums, nor will I continue to support the lab's software through email. I have the highest conf...
by Marshall.Buhl
Thu Aug 14, 2014 2:55 pm
Forum: Computer-Aided Engineering Software Tools
Topic: SOWFA Support
Replies: 52
Views: 45520

SOWFA Support

Please post your SOWFA questions here--especially if others might find the information useful. If no one replies to your question, please send email to Matt.Churchfield@nrel.gov and/or Sang.Lee@nrel.gov. Note that the reason for posting questions here is so that the SOWFA developers will see your qu...
by Marshall.Buhl
Mon Jul 14, 2014 10:30 am
Forum: Computer-Aided Engineering Software Tools
Topic: LSS bending moment
Replies: 9
Views: 3953

Re: LSS bending moment

Dear Mehdi, I'm afraid that I have no idea what Rotor_MY is so I cannot address that issue. I see that the LSSGagMya plot has a mean of 0, so I think that means you have no shaft tilt. For the shaft bending loads, you can easily check them by multiplying the mass of the rotor by the distance from th...
by Marshall.Buhl
Mon Jul 14, 2014 9:26 am
Forum: General
Topic: Pitch Bearing Life
Replies: 3
Views: 3963

Re: Pitch Bearing Life

Dear Dominik, NREL made a brief foray into the certification business back in the 1990s. Included in that effort were reports for design guidelines. I didn't think the DGs were ever completed or published, but I see now that DG03 was. I do know that DG01 was never completed because I was one of the ...
by Marshall.Buhl
Thu Jul 10, 2014 4:34 pm
Forum: Computer-Aided Engineering Software Tools
Topic: LSS bending moment
Replies: 9
Views: 3953

Re: LSS bending moment

Dear Mehdi,

I think those measurements are for virtual strain gages on the shaft and they rotate with the rotor. You should see a 1P gravity load on them.


Marshall
by Marshall.Buhl
Tue Jul 08, 2014 9:49 am
Forum: Computer-Aided Engineering Software Tools
Topic: Platform Motion Initiation
Replies: 3
Views: 2757

Re: Platform Motion Initiation

Dear Kurt, As far as I know, there is no way to enable/disable FAST DoFs at times greater than 0. One possible option would be to model the turbine with the platform DoFs disabled up to the point you want to turn them on, record the state of the non-platform DoFs, and then use them as ICs for anothe...
by Marshall.Buhl
Thu Jul 03, 2014 11:15 am
Forum: Computer-Aided Engineering Software Tools
Topic: FAST: Tower Drag and Tail vane inertia
Replies: 6
Views: 8251

Re: FAST: Tower Drag and Tail vane inertia

Dear Niklas, TurbSim has an option (WrADTWR) to create a "lollypop" wind field with points for the tower. You must use the WrADFF option to generate a binary TurbSim file (*.bts) so the tower points will be included for AeroDyn to use. See Figure 4 on Page 7 of the TurbSim draft manual. Ma...
by Marshall.Buhl
Thu Jul 03, 2014 10:56 am
Forum: Structural Analysis
Topic: constraint equations of the multibody approach
Replies: 3
Views: 3532

Re: constraint equations of the multibody approach

Dear Ethan, Jason is out for about a week, so I thought I'd point you to some documentation you can look at for now. He has often talked about the FAST theory basis here and searching this forum for "fast theory" may help you find a few more articles that will help you. However, his post o...
by Marshall.Buhl
Tue Jul 01, 2014 10:17 am
Forum: Computer-Aided Engineering Software Tools
Topic: Negative Production
Replies: 1
Views: 2393

Re: Negative Production

Dear Fernando,

Well, I consider negative production to be a bad thing. ;-)

But, seriously, would you please be more explicit about what you are asking?


Marshall
by Marshall.Buhl
Tue Jun 24, 2014 5:42 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Aerodyn error Wdir=180 deg
Replies: 3
Views: 2862

Re: Aerodyn error Wdir=180 deg

Dear Gerrit, I have never tried to run with a 180-deg wind direction in the HH files, so it could be that there's a problem with it. I wonder if 540 degrees would work. Otherwise, I suggest trying 179.99. Either that, or yaw the turbine 180 and use a 0-deg wind direction like you would do with FF fi...
by Marshall.Buhl
Tue Jun 24, 2014 5:35 pm
Forum: Computer-Aided Engineering Software Tools
Topic: upwind and downwind turbines
Replies: 7
Views: 4679

Re: upwind and downwind turbines

Dear Marianne, Just to clarify for what I think you are asking, if you take an existing upwind turbine and convert it to a downwind turbine without changing where the CM is within the rotating nacelle coordinate system, you would need to change the sign of the CM. So, if you had an upwind system wit...
by Marshall.Buhl
Fri Jun 13, 2014 3:29 pm
Forum: Computer-Aided Engineering Software Tools
Topic: FAST framework automation.
Replies: 3
Views: 2806

Re: FAST framework automation.

Dear Khaled,

Have you tried creating a simple Windows batch file? If you do not expect the script to modify your input files, it should be easy to write and use.


Marshall
by Marshall.Buhl
Fri May 23, 2014 11:57 am
Forum: Rotor Aerodynamics
Topic: Rgarding AoA- different wnd sped-along same section in blade
Replies: 1
Views: 3781

Re: Rgarding AoA- different wnd sped-along same section in b

Dear Ijaz,

The AoA varies with wind speed, induction, rotor speed, and flexible blade motion.


Marshall
by Marshall.Buhl
Fri May 23, 2014 11:54 am
Forum: Inflow Turbulence
Topic: Turbsim OutputTime and Tmax in FAST
Replies: 5
Views: 6618

Re: Turbsim OutputTime and Tmax in FAST

Dear Minxi, The grid points in the wind file do not align with the analysis nodes on the tower. AeroDyn interpolates the wind file for the tower nodes. If I needed to know the tower loads, I would modify AeroDyn to write them to a file. I think the calculation is done in AD_CalcOutput(). You would p...
by Marshall.Buhl
Thu May 22, 2014 4:21 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Instructions for Compiling FAST
Replies: 200
Views: 114200

Re: Instructions for Compiling FAST

Dear Hamid, I've never tried to compile FAST for MATLAB, but it looks like you need to compile the ModMesh routines before you compile NWTC_Library.f90. Have you included them in your IVF project? Are you using the Visual Studio shell or are you compiling at the command line? The shell will usually ...

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