Calculate TwFAM1Sh(2-6) and TwFAM2Sh(2-6)

Wind & Water Computer-Aided Engineering Software Tools
42

Dear Jason,

Thank you for your response.
We are using the “Improved Direct Method.”

I will also attach the data for the secondary modes of SS and FA, which may be causing the issue.

Mode No. 4 (freq = 0.25611E+01 Hz)
span_loc s-s disp s-s slope f-a disp f-a slope twist
0 0 0 0 0 0
0.0464 0.000615 0.025893 0 0 0.002304
0.0918 0.002365 0.050689 0 0 0.004858
0.1371 0.00523 0.074987 0 0 0.00782
0.1824 0.009171 0.09804 0 0 0.011254
0.2274 0.014063 0.118444 0 0 0.01514
0.2724 0.019777 0.134501 0 0 0.019334
0.3193 0.026372 0.145602 0 0 0.023925
0.3658 0.033278 0.150751 0 0 0.028761
0.4111 0.040112 0.149825 0 0 0.03385
0.4564 0.04676 0.142525 0 0 0.03937
0.5016 0.052901 0.128458 0 0 0.045345
0.5467 0.058252 0.10756 0 0 0.051741
0.5919 0.062513 0.080275 0 0 0.058469
0.6387 0.065474 0.04567 0 0 0.0658
0.6848 0.066637 0.004156 0 0 0.073713
0.7301 0.065701 -0.04591 0 0 0.082612
0.7754 0.06226 -0.10624 0 0 0.092877
0.8309 0.053919 -0.1948 0 0 0.107586
0.8864 0.040306 -0.29594 0 0 0.1243
0.9418 0.02088 -0.40413 0 0 0.142398
1 -0.00614 -0.52438 0 0 0.162997
Mode No. 5 (freq = 0.29057E+01 Hz)
span_loc s-s disp s-s slope f-a disp f-a slope twist
0 0 0 0 0 0
0.0464 0 0 0.000776 0.032636 0
0.0918 0 0 0.002977 0.063642 0
0.1371 0 0 0.006565 0.093707 0
0.1824 0 0 0.011475 0.12181 0
0.2274 0 0 0.017531 0.146141 0
0.2724 0 0 0.024553 0.1646 0
0.3193 0 0 0.032584 0.176413 0
0.3658 0 0 0.040902 0.180465 0
0.4111 0 0 0.049024 0.176707 0
0.4564 0 0 0.056793 0.16485 0
0.5016 0 0 0.063807 0.144605 0
0.5467 0 0 0.06972 0.116182 0
0.5919 0 0 0.074181 0.080479 0
0.6387 0 0 0.076935 0.036685 0
0.6848 0 0 0.077465 -0.01417 0
0.7301 0 0 0.075484 -0.07347 0
0.7754 0 0 0.07059 -0.14239 0
0.8309 0 0 0.059996 -0.23902 0
0.8864 0 0 0.043819 -0.34306 0
0.9418 0 0 0.021865 -0.44685 0
1 0 0 -0.00727 -0.55278 0
43

Dear @Kazuya.Nishiyama,

I’m not sure why, but when I used the ModeShapePolyFitting.xls spreadsheet with your BModes output data, my results are quite different:

Mode No. 4

Normalized Improved Direct Method
-43.6576
-22.8256
111.0691
-59.3065
15.7205

Mode No. 5

Normalized Improved Direct Method
-46.7606
-21.1082
118.3085
-57.1320
7.6922

Note that I set the slope at the bottom equal to zero to match the s-s slope / f-a slope values. Do you get more reasonable OpenFAST response with these revised mode shapes?

Best regards,

44

Dear Jason,

Thank you for your response.

I recalculated using the corrected mode coefficient you provided; however, the same error still occurs.

As a precaution, I will send the Excel file and related materials to you via email.

Best regards,

45

Dear @Kazuya.Nishiyama,

I took a quick look at your files. Just a few comments/questions:

  • Your BModes outputs are bit different than you shared before; why is that?
  • I agree with your you are using ModeShapePolyFitting.xls to fit mode shapes to your new BModes data. But I see that you are using my tower mode shapes (based on your old BModes outputs), not your new tower mode shapes based on fitting with the new data; why is that?
  • Your tower stiffness is quite a bit less than the original; why is that?
  • I see a few changes you made relative to the original r-test of the WindPACT 1.5-MW baseline turbine (including the tower distributed mass/stiffness, tower mode shapes, wind inflow, initial rotor speed, and the initial blade pitch), but it is not obvious to me which of these changes are triggering the simulation error. I suggest making the changes one by one to isolate which change relative to the original r-test triggers the issue.

Best regards,

46

Dear Jason,

Thank you for your response.

As you suggested, I was able to identify the cause by changing the parameters one by one. The issue was due to the low initial rotation speed. When it was set to 10 rpm, an error occurred; however, when set to 11 rpm or higher, no error appeared and the analysis could be carried out successfully.

Best Regards

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