Questions regarding blade azimuth

[TorbenKnudsen]

I have the following lines in ElastoDyn.dat containing azimuth
0 Azimuth - Initial azimuth angle for blade 1 (degrees)
0 AzimB1Up - Azimuth value to use for I/O when blade 1 points up (degrees)
"Azimuth" - Blade 1 azimuth angle
Also I am using "standard" NREL5MW
I have consulted FAST User's Guide, NREL/TP-500-38230, October 2005, J.M. Jonkman, M.L. Buhl Jr.
Still, I like to get something confirmed.

Is it correct for the NREL5MW that

• TipDxb1 is positive down wind?
• Azimuth increases in the rotational direction?
• Azimuth output variable is for blade 1?
• The blade sequence is 3-2-1?
• So when azimuth of blade 1 is 0 it is 120 for blade 2 and 240 for blade 3?

[jjonkman]

Dear @TorbenKnudsen,

I agree with all of your bullets about the azimuth.

Regarding TipDxb1, the blade (b) coordinate system pitches with the blade, so, the local xb axis need not be pointed downwind, but that is the case when the yaw and pitch angles are both zero.

Best regards,