Dear All,
I am trying to generate a turbulent wind field at rated wind speed on the NREL 5MW reference wind turbine by using TURBSIM. I am able to run the analysis and visualize the wind field output by using QBlade. When I check the wind field, I see a horizontal layer of discontinuity which elevates in each time step as seen in the attached figure. Has anyone experienced something similar?
Wind field is generated according to;
- 0.01581 seconds of time step
- Kaimal spectrum
- IEC 61400-3
- normal turbulence
- wind-speed profile: power shear law
- Spatial Coherence parameters according to: IEC
Turbsim input file and the image is attached to the post. Thanks in advance for any suggestion.
Sincerely,
Mustafa
TurbSim.rar (2.49 KB)
Dear Mustafa,
Your image does not look like what I would expect to see. And I don’t see that you shared your input file to review.
I’m not familiar with QBlade’s wind field output, but could there be a problem with how this data is visualized? NREL has provided a MATLAB-based reader, readfile_BTS.m, which can load the data from the TurbSim binary output file into MATLAB for plotting. You can find this reader in the MATLAB Toolbox: github.com/OpenFAST/matlab-tool … /Utilities.
Best regards,
Dear Jason,
Thanks a lot for your help and your time. My apologies for the lack of input file. Its available now. I’ll check the MATLAB-based reader output and update here.
Sincerely,
Mustafa
Dear Mustafa,
I don’t see anything out of the ordinary from my quick skip of your TurbSim input file. Let us know what the MATLAB-based plot reveals.
Best regards,
Dear Jason,
Thanks a lot for sharing your time and help. I used the "readfile_BTS " script with “FFwind_figure” script (Visualize full-field Turbsim data and anemometer equivalent wind speed - #13 by Jason.Jonkman) to visualize the turbulent wind field.
Attached figures show the u, v and w components of the turbulent wind field at t=250.304 seconds. I could not see any discontinuity in the plots. Can you see anything unusual?
I’ve also crosschecked the output (wind field plot) of QBlade by exporting the imported windfield from QBlade into a text file. It seems like (not sure) QBlade exports the resultant wind speed. Checked David’ Marten’s thesis and QBlade manual but did not see an information. Noticed the same discontinuity problem in a post on QBlade forum and raised a question under the same post: sourceforge.net/p/qblade/discus … /?limit=25
Will inform here if I get anything from QBlade forum.
Thanks in advance for your help.
Sincerely,
Mustafa
Dear Mustafa,
OK, thanks for the update. I don’t see anything unusual in these plots. Sounds like the problem may be with the QBlade visualizer.
Best regards,
Dear Jason & Dear All,
I would like to ask your opinion about the plots I shared here previously (April 25). I see wind speed differences between each square in v-component (also w) of the wind field. Though the extreme values are lower than u-component extremes in the colorbar, seeing next to each other yellow (+4 to +6 m/s) and blue squares (-4 to -6 m/s) makes me think about it.
Thanks in advance for your time and suggestions.
Sincerely,
Mustafa
Dear Mustafa,
It looks like this wind field was created with consideration of spatial coherence in the v- and w- components. This is a feature that can be enabled/disabled in TurbSim.
Best regards,
Dear Jason,
Thank you as always for your help.
1-You have the point. Previously “SCMod1”, “SCMod2” and “SCMod1” were all set to “IEC”. When I set all the three parameters to “NONE”, wind field u-component changes drastically but have not noticed any difference with v and w-components as in the image:
2-When I execute TURBSIM with the three parameters set to “default”, I am getting exactly the same plot as I got previously in the image from April 25. I would like to note that I am using “IECKAI” (Kaimal spectrum) for the turbulence model. In this case v and w component spatial coefficients are set to “NONE” according to Table 9 of TURBSIM user manual.
3-I also tried changing the seed but again I see this low correlation in v or w components.
In any case I am uploading the input files again.
Sincerely,
Mustafa
TurbSim.rar (7.71 KB)
Dear Mustafa,
I agree, that the “DEFAULT” option is no spatial coherence in the v- and w-components; this is because default values are not specified in the IEC design standards.
But to obtain spatial coherence of the v- and w-components, you can set SCMod2 = SCMod3 = “IEC” and then specify InCDec2, InCDec3, and CohExp. To use the same values in v and w that are used by u, you can set InCDec2 = InCDec3 = “12.0 0.00035273” and CohExp = 0.0.
Best regards,
