Dear Lingling,
Here are the data I get (calculated by ADAMS) regarding the mass & inertia of the rigid rotor-nacelle assembly (RNA) for the NREL 5-MW turbine:
Mass : 3.500003109E+005 kg
Center of Mass :
Location : -0.4137754432, -8.3126516178E-009, 1.9669893542 (meter, meter, meter)
Orientation : 359.9999911963, 90.0000955298, 354.6136364306 (deg)
Mass Inertia Tensor :
IXX : 4.5050443961E+007 kg-meter2
IYY : 2.4940615741E+007 kg-meter2
IZZ : 2.5477667652E+007 kg-meter2
IXY : 0.2010825213 kg-meter2
IZX : 1.4540376371E+006 kg-meter2
IYZ : 2.8803379356 kg-meter2
The center-of-mass (CM) location, orientation, and inertias above are all relative to FAST’s nacelle coordinate system, which originates at the yaw bearing (i.e., tower top) with “X” pointing downwind, “Y” pointing to the left when looking downwind, and “Z” pointing vertically upwards.
Some of the values you report are close to these; others (especially the Z-coordinate of the CM and the IXX and IYY inertias) are quite a bit different because you’ve output yours relative to the global reference frame.
However, what BModes needs as input is the inertias of the RNA specified relative ot the CM of the RNA. Here are the inertias I report above translated to the CM of the RNA:
Ixx = 4.370E7 kgm^2
Iyy = 2.353E7 kgm^2
Izz = 2.542E7 kgm^2
Izx = 1.169E6 kgm^2
See my Nov 23, 2009 post in the forum topic found here for more information: Tower fore-aft modes shapes.
I hope that helps!
Best regards,