Marshall,
This is partly a question about IEC Wind and partly a question of standards.
The GenEWS routine has a commented out value of alpha which was used in the determination of v(z,t) via ShrMax; now the params value of alpha is used, whose value is dependent on whether 61400-1 or 61400-3 is specified.
Code: Select all
SUBROUTINE GenEWS (FileNum)
! Generate the EWS condition.
USE Params
IMPLICIT NONE
! Passed variables
INTEGER FileNum
! Local variables
!mlb Start of proposed change.
!REAL ::Alpha = 0.2 !Shear definition constant
!mlb Start of proposed change...
...
!mlb Start of proposed change.
!ShrMax=2.*(2.5+0.2*VG50*(TurbRat)**0.25)/Vhub
ShrMax=2.*(2.5+Alpha*VG50*(TurbRat)**0.25)/Vhub...
Eqn 26 of IEC 61400-1 contains a 0.2, which is not a variable but which has been interpreted in IECWind as the variable alpha and therefore varies with 61400-x. Do you know why this was made a variable? I can't find a justification in 61400-3. Seems especially unusual if it is the vertical shear exponent as it influences the horizontal shear. Can you help me understand?
Rebecca