I am confused by the NRELOffshrBsline5MW_Blade.dat
---------------------- BLADE ADJUSTMENT FACTORS --------------------------------
1 FlStTunr(1) - Blade flapwise modal stiffness tuner, 1st mode (-)
1 FlStTunr(2) - Blade flapwise modal stiffness tuner, 2nd mode (-)
1.04536 AdjBlMs - Factor to adjust blade mass density (-) !bjj: value for AD14=1.04536; value for AD15=1.057344 (it would be nice to enter the requested blade mass instead of a factor here)
1 AdjFlSt - Factor to adjust blade flap stiffness (-)
1 AdjEdSt - Factor to adjust blade edge stiffness (-)
---------------------- DISTRIBUTED BLADE PROPERTIES ----------------------------
BlFract PitchAxis StrcTwst BMassDen FlpStff EdgStff
(-) (-) (deg) (kg/m) (Nm^2) (Nm^2)
0.0000000E+00 2.5000000E-01 1.3308000E+01 6.7893500E+02 1.8110000E+10 1.8113600E+10
3.2500000E-03 2.5000000E-01 1.3308000E+01 6.7893500E+02 1.8110000E+10 1.8113600E+10
1.9510000E-02 2.5049000E-01 1.3308000E+01 7.7336300E+02 1.9424900E+10 1.9558600E+10
3.5770000E-02 2.5490000E-01 1.3308000E+01 7.4055000E+02 1.7455900E+10 1.9497800E+10
what does AdjBlMs mean? Will BMassDen be multiplied by the coefficient AdjBlMs during calculation?
Now I am using aerodyn15. Do I need to change AdjBlMs to 1.057344?
Is there any documentation describing the meaning of parameters in NRELOffshrBsline5MW_Blade.dat. What are PitchAxis and StrcTwst?
Could anyone please share me the input file of BModes for this 5MW blade? I want to do a simulation to check whether I can get the same mode shape coefficients for blade.
Thank you @Jason.Jonkman .
Is StrcTwst is actually the same definition and value with BlTwist in NRELOffshrBsline5MW_AeroDyn_blade.dat?
Below figure is the cross-section of blade. It explained the BlTwist (it is the orientation of the local chord about the vector normal to the plane of the airfoil). I want to know whether the origin of these axis is the aerodynamic center (reference point for the airfoil lift and drag forces)?
It seems that Aerodyn15 defines all blade data on aerodynamic centers of cross-section. For example, BlCrvAC specifies the local out-of-plane offset of the aerodynamic center normal to the blade-pitch axis. For Elastodyn, I am guessing whether BlFract and StrcTwst are also defined based on aerodynamic centers. And FlpStff is the bending stiffness around local blade chordline with origin at aerodynamic centers. EdgStffin is the bending stiffness around the in-plane axis perpendicular to local blade chordline with origin at aerodynamic centers
Dear @Jason.Jonkman ,
I found that aerodynamic center of blade cross-section is defined twice.
In NRELOffshrBsline5MW_AeroDyn_blade.dat, aerodynamic center is defined by BlCrvAC and BlSwpAC. But in Airfoils folder, it is also defined in “NumCoords”. The first point in “NumCoords” must always locate the aerodynamic center.
Although above two aerodynamic centers are defined in different reference frame, I am confused that these two aerodynamic centers must be located at the same position?
If they are different, which one is really used to calculate the aerodynamic load in Aerodyn15?
Or “NumCoords” in airfoils folder actually is only for surface visualization, and will not affect the calculation results?
The values of
BlSwpAC define the aerodynamic center relative to the pitch axis and are used in the aerodynamic calculations (e.g., offsets from the pitch axis will create pitching moments). Within the airfoil data file, the shape of the airfoil is defined relative to the aerodynamic center, not the pitch axis, but these data are only used for visualization, not in any calculation.