Dear Jason,
I tried to implement a BEM code in MATLAB, using the Distributed Blade Aerodynamic Properties of the 5MW NREL wind turbine (Table 3-1 in the 5MW NREL reference pdf: nrel.gov/docs/fy09osti/38060.pdf) and the airfoils data. I find the maximum power coefficient of Cp_max=0.486 at TSR=7.82 and Pitch=0.0°, which are slightly off what is in the pdf reference (Cp_max=0.482 and TSR=7.55). Here is a plot of Cp with TSR and Pitch angle.
I have two questions:
_ Is this tiny difference comes from the number of blade nodes taken?
_ Are those results that I found make sense to you?
Dear Younes,
Yes, these results are quite similar to the ones generated by NREL. Differences could be the result of discretization (which could easily checked by studying the convergence with increasing number of nodes) or by differences in the underlying BEM assumptions (more difficult to assess).
Best regards,
Dear Jason,
Thank you so much for the reply. I am wondering if there is a Cp table for the 5MW NREL wind turbine that we can use, or should we compute it ourselves? I see that WT_Perf is not available anymore.
Kindest regards
Younes
Dear Younes,
The Cp table for NREL 5-MW baseline wind turbine is available in one of the earlier posts in this forum topic above.
Best regards,
Dear Jason,
Thank you for the tables. I am interested in looking at the variation of the Cp in the table in the different regions. From the 5MW NREL documentation, in region 3, the pitch angle goes up to 25 degrees. But in the CpVersusTSR&Pitch_WT_Perf.xlsx table, the Cp table is limited to 5 degrees at maximum. Is there an open-source software like WT_Perf to compute it with a desired pitch angle range and TSR range?
Sorry for the inconvenience
Kindest regards
Younes
Dear Younes,
The standalone driver for AeroDyn (uncoupled from OpenFAST) can be used as a replacement for WT_Perf. The CCBlade module of the systems engineering tool WISDEM can also be used.
Best regards,
Dear Jason,
Thank you for the precise reply. I use AeroDyn as suggested, but I still have the same issue: I don’t find the Cp=0.48 at TSR_opt=7.55 for pitch=0°. The maximum Cp I get is 0.46 as you can see in the figure below (from AeroDyn):
I tried to change the nodes in AeroDyn_blade.dat, replacing them with the ones taken from WT_Perf input file. But I still can’t reach a power coefficient of 0.48. I don’t know what I am missing to get the right values. Do you have any suggestions please?
Here is my DRV input file:
----- AeroDyn Driver v1.00.x Input File --------------------------------------
NRELOffshrBsline5MW_Onshore_AeroDyn15.dat
----- Input Configuration ----------------------------------------------------
FALSE Echo - Echo input parameters to "<rootname>.ech"?
"NRELOffshrBsline5MW_Onshore_AeroDyn15_Test01.dat" AD_InputFile - Name of the primary AeroDyn input file
----- Turbine Data -----------------------------------------------------------
3 NumBlades - Number of blades (-)
1.5 HubRad - Hub radius (m)
90 HubHt - Hub height (m)
-5.0191 Overhang - Overhang (m)
-5 ShftTilt - Shaft tilt (deg)
-2.5 Precone - Blade precone (deg)
----- I/O Settings -----------------------------------------------------------
"" OutFileRoot - Root name for any output files (use "" for .dvr rootname) (-)
True TabDel - When generating formatted output (OutForm=True), make output tab-delimited (fixed-width otherwise) (flag)
"ES15.6E3" OutFmt - Format used for text tabular output, excluding the time channel. Resulting field should be 10 characters. (quoted string)
True Beep - Beep on exit (flag)
----- Combined-Case Analysis -------------------------------------------------
200 NumCases - Number of cases to run
WndSpeed ShearExp RotSpd Pitch Yaw dT Tmax
(m/s) (-) (rpm) (deg) (deg) (s) (s)
8.0000000e+00 0.0000000e+00 2.2080000e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 2.2577085e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 2.3074171e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 2.3571256e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 2.4068342e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 2.4565427e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 2.5062513e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 2.5559598e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 2.6056683e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 2.6553769e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 2.7050854e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 2.7547940e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 2.8045025e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 2.8542111e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 2.9039196e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 2.9536281e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.0033367e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.0530452e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.1027538e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.1524623e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.2021709e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.2518794e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.3015879e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.3512965e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.4010050e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.4507136e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.5004221e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.5501307e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.5998392e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.6495477e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.6992563e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.7489648e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.7986734e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.8483819e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.8980905e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.9477990e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 3.9975075e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.0472161e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.0969246e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.1466332e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.1963417e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.2460503e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.2957588e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.3454673e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.3951759e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.4448844e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.4945930e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.5443015e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.5940101e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.6437186e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.6934271e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.7431357e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.7928442e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.8425528e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.8922613e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.9419698e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 4.9916784e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.0413869e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.0910955e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.1408040e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.1905126e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.2402211e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.2899296e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.3396382e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.3893467e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.4390553e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.4887638e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.5384724e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.5881809e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.6378894e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.6875980e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.7373065e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.7870151e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.8367236e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.8864322e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.9361407e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 5.9858492e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.0355578e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.0852663e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.1349749e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.1846834e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.2343920e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.2841005e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.3338090e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.3835176e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.4332261e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.4829347e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.5326432e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.5823518e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.6320603e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.6817688e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.7314774e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.7811859e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.8308945e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.8806030e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.9303116e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 6.9800201e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.0297286e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.0794372e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.1291457e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.1788543e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.2285628e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.2782714e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.3279799e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.3776884e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.4273970e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.4771055e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.5268141e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.5765226e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.6262312e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.6759397e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.7256482e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.7753568e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.8250653e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.8747739e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.9244824e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 7.9741910e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.0238995e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.0736080e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.1233166e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.1730251e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.2227337e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.2724422e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.3221508e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.3718593e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.4215678e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.4712764e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.5209849e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.5706935e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.6204020e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.6701106e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.7198191e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.7695276e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.8192362e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.8689447e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.9186533e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 8.9683618e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.0180704e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.0677789e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.1174874e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.1671960e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.2169045e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.2666131e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.3163216e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.3660302e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.4157387e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.4654472e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.5151558e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.5648643e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.6145729e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.6642814e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.7139899e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.7636985e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.8134070e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.8631156e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.9128241e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 9.9625327e+00 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0012241e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0061950e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0111658e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0161367e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0211075e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0260784e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0310492e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0360201e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0409910e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0459618e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0509327e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0559035e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0608744e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0658452e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0708161e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0757869e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0807578e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0857286e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0906995e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.0956704e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1006412e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1056121e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1105829e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1155538e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1205246e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1254955e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1304663e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1354372e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1404080e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1453789e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1503497e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1553206e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1602915e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1652623e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1702332e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1752040e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1801749e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1851457e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1901166e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.1950874e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.2000583e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.2050291e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
8.0000000e+00 0.0000000e+00 1.2100000e+01 0.0000000e+00 0.0000000e+00 1.3800000e-01 1.0000000e+01
Sorry for the inconvenience
Kindest regards
Younes
Dear Younes,
What aerodynamic modeling options have you selected in AeroDyn?
It could be, though, that AeroDyn has an implementation of BEM that is different from WT_Perf, so, I would not expect identical agreement.
I have not actually used the standalone AeroDyn driver to derived the Cp curve myself, but many years we did perform such an analysis in FAST with structural DOFs enabled. The response is also a bit different due to the influence of blade deflection.
Best regards,
Dear Jason,
Thank you for the reply. I changed the aerodynamic modeling to steady model AFAeroMod=1, and I got closer results. But I still have differences such as the maximum Cp is found at pitch -1° and TSR of 7.3 as you can see in the figures below.
Maybe I have the wrong parameters in my AeroDyn and AeroDyn_blade files. Here are they:
AeroDyn:
------- AERODYN v15.04.* INPUT FILE ------------------------------------------------
NREL 5.0 MW offshore baseline aerodynamic input properties.
====== General Options ============================================================================
False Echo - Echo the input to "<rootname>.AD.ech"? (flag)
"default" DTAero - Time interval for aerodynamic calculations {or "default"} (s)
1 WakeMod - Type of wake/induction model (switch) {0=none, 1=BEMT}
1 AFAeroMod - Type of blade airfoil aerodynamics model (switch) {1=steady model, 2=Beddoes-Leishman unsteady model} [must be 1 when linearizing]
0 TwrPotent - Type tower influence on wind based on potential flow around the tower (switch) {0=none, 1=baseline potential flow, 2=potential flow with Bak correction}
False TwrShadow – Calculate tower influence on wind based on downstream tower shadow? (flag)
True TwrAero - Calculate tower aerodynamic loads? (flag)
False FrozenWake - Assume frozen wake during linearization? (flag) [used only when WakeMod=1 and when linearizing]
False CavitCheck - Perform cavitation check? (flag)
====== Environmental Conditions ===================================================================
1.225 AirDens - Air density (kg/m^3)
1.4639E-05 KinVisc - Kinematic air viscosity (m^2/s)
335 SpdSound - Speed of sound (m/s)
103500 Patm - Atmospheric pressure (Pa) [used only when CavitCheck=True]
1700 Pvap - Vapour pressure of fluid (Pa) [used only when CavitCheck=True]
0.1 FluidDepth - Water depth above mid-hub height (m) [used only when CavitCheck=True]
====== Blade-Element/Momentum Theory Options ====================================================== [used only when WakeMod=1]
1 SkewMod - Type of skewed-wake correction model (switch) {1=uncoupled, 2=Pitt/Peters, 3=coupled} [used only when WakeMod=1]
True TipLoss - Use the Prandtl tip-loss model? (flag) [used only when WakeMod=1]
true HubLoss - Use the Prandtl hub-loss model? (flag) [used only when WakeMod=1]
true TanInd - Include tangential induction in BEMT calculations? (flag) [used only when WakeMod=1]
False AIDrag - Include the drag term in the axial-induction calculation? (flag) [used only when WakeMod=1]
False TIDrag - Include the drag term in the tangential-induction calculation? (flag) [used only when WakeMod=1 and TanInd=TRUE]
5E-05 IndToler - Convergence tolerance for BEMT nonlinear solve residual equation {or "default"} (-) [used only when WakeMod=1]
10000 MaxIter - Maximum number of iteration steps (-) [used only when WakeMod=1]
====== Beddoes-Leishman Unsteady Airfoil Aerodynamics Options ===================================== [used only when AFAeroMod=2]
3 UAMod - Unsteady Aero Model Switch (switch) {1=Baseline model (Original), 2=Gonzalez’s variant (changes in Cn,Cc,Cm), 3=Minemma/Pierce variant (changes in Cc and Cm)} [used only when AFAeroMod=2]
True FLookup - Flag to indicate whether a lookup for f' will be calculated (TRUE) or whether best-fit exponential equations will be used (FALSE); if FALSE S1-S4 must be provided in airfoil input files (flag) [used only when AFAeroMod=2]
====== Airfoil Information =========================================================================
1 InCol_Alfa - The column in the airfoil tables that contains the angle of attack (-)
2 InCol_Cl - The column in the airfoil tables that contains the lift coefficient (-)
3 InCol_Cd - The column in the airfoil tables that contains the drag coefficient (-)
4 InCol_Cm - The column in the airfoil tables that contains the pitching-moment coefficient; use zero if there is no Cm column (-)
0 InCol_Cpmin - The column in the airfoil tables that contains the Cpmin coefficient; use zero if there is no Cpmin column (-)
8 NumAFfiles - Number of airfoil files used (-)
"Airfoils\NREL_5MW\Cylinder1_10Hz.dat" AFNames - Airfoil file names (NumAFfiles lines) (quoted strings)
"Airfoils\NREL_5MW\Cylinder2_10Hz.dat"
"Airfoils\NREL_5MW\DU40_A17_10Hz.dat"
"Airfoils\NREL_5MW\DU35_A17_10Hz.dat"
"Airfoils\NREL_5MW\DU30_A17_10Hz.dat"
"Airfoils\NREL_5MW\DU25_A17_10Hz.dat"
"Airfoils\NREL_5MW\DU21_A17_10Hz.dat"
"Airfoils\NREL_5MW\NACA64_A17_10Hz.dat"
====== Rotor/Blade Properties =====================================================================
True UseBlCm - Include aerodynamic pitching moment in calculations? (flag)
"NRELOffshrBsline5MW_AeroDyn_blade.dat" ADBlFile(1) - Name of file containing distributed aerodynamic properties for Blade #1 (-)
"NRELOffshrBsline5MW_AeroDyn_blade.dat" ADBlFile(2) - Name of file containing distributed aerodynamic properties for Blade #2 (-) [unused if NumBl < 2]
"NRELOffshrBsline5MW_AeroDyn_blade.dat" ADBlFile(3) - Name of file containing distributed aerodynamic properties for Blade #3 (-) [unused if NumBl < 3]
====== Tower Influence and Aerodynamics ============================================================= [used only when TwrPotent/=0, TwrShadow=True, or TwrAero=True]
12 NumTwrNds - Number of tower nodes used in the analysis (-) [used only when TwrPotent/=0, TwrShadow=True, or TwrAero=True]
TwrElev TwrDiam TwrCd
(m) (m) (-)
0.0000000E+00 6.0000000E+00 1.0000000E+00
8.5261000E+00 5.7870000E+00 1.0000000E+00
1.7053000E+01 5.5740000E+00 1.0000000E+00
2.5579000E+01 5.3610000E+00 1.0000000E+00
3.4105000E+01 5.1480000E+00 1.0000000E+00
4.2633000E+01 4.9350000E+00 1.0000000E+00
5.1158000E+01 4.7220000E+00 1.0000000E+00
5.9685000E+01 4.5090000E+00 1.0000000E+00
6.8211000E+01 4.2960000E+00 1.0000000E+00
7.6738000E+01 4.0830000E+00 1.0000000E+00
8.5268000E+01 3.8700000E+00 1.0000000E+00
8.7600000E+01 3.8700000E+00 1.0000000E+00
====== Outputs ====================================================================================
False SumPrint - Generate a summary file listing input options and interpolated properties to "<rootname>.AD.sum"? (flag)
5 NBlOuts - Number of blade node outputs [0 - 9] (-)
4, 5, 6, 8, 9 BlOutNd - Blade nodes whose values will be output (-)
0 NTwOuts - Number of tower node outputs [0 - 9] (-)
1, 2, 3, 4, 5 TwOutNd - Tower nodes whose values will be output (-)
OutList - The next line(s) contains a list of output parameters. See OutListParameters.xlsx for a listing of available output channels, (-)
"RtAeroCp"
"RtSpeed"
"RtTSR"
"RtVAvgxh"
END of input file (the word "END" must appear in the first 3 columns of this last OutList line)
---------------------------------------------------------------------------------------
AeroDyn_blade:
------- AERODYN v15.00.* BLADE DEFINITION INPUT FILE -------------------------------------
NREL 5.0 MW offshore baseline aerodynamic blade input properties
====== Blade Properties =================================================================
18 NumBlNds - Number of blade nodes used in the analysis (-)
BlSpn BlCrvAC BlSwpAC BlCrvAng BlTwist BlChord BlAFID
(m) (m) (m) (deg) (deg) (m) (-)
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.3308000E+01 3.5420000E+00 1
2.8667000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.3308000E+01 3.5420000E+00 1
5.6000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.3308000E+01 3.8540000E+00 1
8.3333333E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.3308000E+01 4.1670000E+00 2
1.1750000E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.3308000E+01 4.5570000E+00 3
1.5850000E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.1480000E+01 4.6520000E+00 4
1.9950000E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0162000E+01 4.4580000E+00 4
2.4050000E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 9.0110000E+00 4.2490000E+00 5
2.8150000E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 7.7950000E+00 4.0070000E+00 6
3.2250000E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 6.5440000E+00 3.7480000E+00 6
3.6350000E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 5.3610000E+00 3.5020000E+00 7
4.0450000E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 4.1880000E+00 3.2560000E+00 7
4.4550000E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 3.1250000E+00 3.0100000E+00 8
4.8650000E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 2.3190000E+00 2.7640000E+00 8
5.2750000E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.5260000E+00 2.5180000E+00 8
5.6166700E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 8.6300000E-01 2.3130000E+00 8
5.8900000E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 3.7000000E-01 2.0860000E+00 8
6.1633333E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0600000E-01 1.4190000E+00 8
Kindest regards
Younes
Dear Jason,
By changing the nodes in the AeroDyn_blade by the one given in Test01 of the AeroDyn files and running it at AFAeroMod=1, I got the Cp at the right pitch angle and TSR as shown below.
AeroDyn_blade for 5MW NREL:
[code]------- AERODYN v15.00.* BLADE DEFINITION INPUT FILE -------------------------------------
NREL 5.0 MW offshore baseline aerodynamic blade input properties
====== Blade Properties =================================================================
19 NumBlNds - Number of blade nodes used in the analysis (-)
BlSpn BlCrvAC BlSwpAC BlCrvAng BlTwist BlChord BlAFID
(m) (m) (m) (deg) (deg) (m) (-)
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.3308000E+01 3.5420000E+00 1
1.3666500E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.3308000E+01 3.5420000E+00 1
4.0999500E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.3308000E+01 3.8540000E+00 1
6.8332500E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.3308000E+01 4.1670000E+00 2
1.0249950E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.3308000E+01 4.5570000E+00 3
1.4349950E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.1480000E+01 4.6520000E+00 4
1.8449950E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0162000E+01 4.4580000E+00 4
2.2549950E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 9.0110000E+00 4.2490000E+00 5
2.6649950E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 7.7950000E+00 4.0070000E+00 6
3.0749950E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 6.5440000E+00 3.7480000E+00 6
3.4849950E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 5.3610000E+00 3.5020000E+00 7
3.8949950E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 4.1880000E+00 3.2560000E+00 7
4.3049950E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 3.1250000E+00 3.0100000E+00 8
4.7149950E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 2.3190000E+00 2.7640000E+00 8
5.1249950E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.5260000E+00 2.5180000E+00 8
5.4666650E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 8.6300000E-01 2.3130000E+00 8
5.7399950E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 3.7000000E-01 2.0860000E+00 8
6.0133250E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0600000E-01 1.4190000E+00 8
6.1499900E+01 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0600000E-01 1.4190000E+00 8
[/code]
Thank you so much for the help and the guidance!
Kindest regards
Younes
Dear Younes,
I’m glad you now get the result you were expecting.
Best regards,
Dear Jason Jonkman,
My question is indirectly related to FAST, and I would appreciate an answer if possible.
I am currently using a floating wind farm model (FOWFSim-Dyn) that uses the characteritics of the NREL 5-MW Semi-Submersible. I am using this model to study the impact of turbine repositionning on wind farm power production. Here, I simulated a wind farm composed of three turbines aligned in the direction of the wind. Each turbine is equipped with a controller that adjusts the turbine control inputs in response to a setpoint of position and power. Additionally, the controller uses aerodynamic stall regulation (with only negative pitch angles) as this regulation generates more thrust required for repositioning.
During the simulation, each turbine have to maximize their power production (according to the power curve of the NREL-5MW) while going to the prescribed positions. Here are the evolution the Cp and Ct coefficients for an incident wind of 14 m/s (the repositionning task starts at 500 s, just ignore the values before that):
The Cp and Ct coefficients were empirically obtained from a precedent study using simulations under FAST and are represented in the form of tables Ct(Lambda,TSR) and Cp(Lambda,TSR). My question is: do the Cp and Ct coefficients maintained by the turbines seem correct or physically possible here? In fact, I am questioning the accuracy of these simulations because I believe that the induction factor must exceed 0.5 to obtain certain values (at some points, Ct briefly exceed 1 for some simulations). Could it be possible that the tables are inaccurate or this situation is just possible in some cases?
Best regards
Timothé Jard
Dear @Timothe.Jard,
For the NREL 5-MW baseline wind turbine, I would consider:
- valid Cp between 0-0.49, depending on the TSR and pitch
- valid Ct between 0.05-1.8, depending on the TSR and pitch, although Ct higher than about 1.1 are off-design conditions.
Best regards
Dear Jason Jonkman,
Thank you for your response, at least it is reassuring that the values seems logical and are contained within these intervals. Furthermore, I was wondering if there is a way (perhaps iteratively) to determine the axial induction factor of each wind turbine based on these combinations of coefficients and other parameters (such as TSR and blade pitch angle)?
Best Regards,
Timothé
Dear @Timothe.Jard,
For low thrust conditions, you could certainly use the classic momentum region of BEM to estimate the rotor-averaged induction from the rotor-averaged thrust coefficient, i.e.:
Ct = 4*a(1-a) → a = 1/2*(1-SQRT(1-Ct))
At higher thrust you’d have to apply, e.g., Glauert correction.
Best regards,
Dear Jason Jonkman,
Thank you for your reply.
As all my mean thurst coefficients are less than 0.96 (meaning a<0.4), I can now assume that the BEM theory is valid here.
Best Regards,
Timothé Jard
