Dear NWTC,
I am attempting to use AeroDyn 12.58, ADAMS2AD 12.20, and Adams/Solver 2008r1 to predict the rotor speed at flutter onset for a large wind turbine design. For this analysis it will be critical to determine the blade element and aerodynamic force orientations as accurately as possible. Through my work I’ve become concerned about the following code from the GetPitRad() subroutine within ADAMS2AD:
!!~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!! Pitch angle is obtained from markers on blade and hub
!! PITNOW = Pitch angle of the current blade section
!! including live twist effects
!! Get Euler angles between the blade aerodynamics marker
!! and the pitch reference marker on the hub.
!! JASON: THIS CALL WILL NOT WORK WHEN THERE IS SUBSTANTIAL BLADE DEFLECTION
!! (OR SUBSTANTIAL BLADE PREBEND), SINCE THE X-AXIS OF MARKER IAERO AND
!! THE X-AXIS OF THE Hub Ref Marker WILL NOT BE PARALLEL!!!
!! THIS IS A SERIOUS PROBLEM THAT MUST BE FIXED FOR FLEXIBLE BLADES
!! AND/OR BLADES WITH PRECURVE AND/OR PRESWEEP!!!!
IVEC(1) = IAERO
IVEC(2) = IPITCH + 100 * ( IBLADE -1 ) ! Hub Ref Marker
NVEC = 2
CALL SYSFNC ( 'AX', IVEC, NVEC, ELPITCH, ERRFLG )
IF ( ERRFLG ) THEN
MESAGE = 'Error calling SYSFNC for pitch angle.'
CALL ERRMES ( ERRFLG , MESAGE , IDADAMS , 'STOP' )
END IF
PitAng = - ELPITCH
!!~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Does there exist a NWTC document of known ADAMS2AD issues? This would be helpful in understanding the consequences of any approximations that are used within the code?
For example, in my present flutter analysis project I am currently investigating whether the Aerodyn PITNOW variable is being correctly calculated at outboard blade stations where large elastic twists and deflections are occurring. For this work it would be extremely helpful to have a resource that would enable me to cross check my own results against previously identified issues.
Thank you,
Cole Rogers