AEROCOEFF
AEROCOEFF, AeroModeType,
AeroMappedFileNames, AeroSpecs,
AeroScalar, nBlades, AutoFileRead
Computes the aero-damping and stiffness coefficients and writes them to an APDL
array.
-
AeroModeType Mode type to be used.
BLADE
—
Non-cyclic cantilevered blade mode (default)
-
AeroMappedFiles Name of string array containing file names of mapped pressures from CFD. The file names should be ordered to correspond to the
AeroSpecsarray.-
AeroSpecs Name of numerical array containing data organized to correspond to the
AeroMappedFilesarray. See the "Notes" section for specific information that must be in the array.-
AeroScalar Scaling value(s) to handle any modal scaling difference between structural and CFD modes. The values can be entered as a scalar or 1-dimensional array. (each scaling value defaults to 1)
-
nBlades Number of blades.
AutoFileReadKey to automatically read and use values from CFD file header.
0 (OFF or NO)
—
Do not read scaling values or nodal diameter from the CFD file header. (default)
1 (ON or YES)
—
Read scaling values (labeled
Mode Multiplierin CFD file) from CFD file header. The scaling values read will be used in calculations and theAeroScalarinput will be ignored. The nodal diameter values will be used to cross check the value of i (input throughAeroSpecsarray).
Notes
The AEROCOEFF command is designed to generate an array of aerodynamic coefficients that
can be used in a cyclic mode-superposition harmonic response analysis using the
CYCFREQ,AERO command to represent aerodynamic stiffness and damping.
These aerodynamic coefficients can also be used in a damped modal analysis phase
(CYCFREQ,MODAL) of a cyclic mode-superposition harmonic solve. An APDL
array called JobnameAeroArray is generated using the
AEROCOEFF command. This array is compatible with the array needed for the
CYCFREQ,AERO command.
The format of the written array follows that of the CYCFREQ,AERO command. The array is formatted as follows:
where
 = the ith interblade phase angle
(IBPA) |
 = the mth vibrating blade mode |
 = the nth blade mode generating the pressure
oscillations |
 and  = the real and imaginary coefficients. |
Prior to issuing the AEROCOEFF command, a non-cyclic cantilevered blade modal analysis must be run, either stress-free or prestressed using linear perturbation. For more information, see Modal Analysis in the Structural Analysis Guide. The file requirements for the AEROCOEFF command are the same as those needed for modal restart as described in Modal Analysis Restart.
The AeroSpecs values are specified in a 3×r array
(*DIM), where r is a positive integer equal to the number of interblade
phase angles and the pressure modes solved for in the CFD analysis. Each row has the
structure:
where
 = the ith interblade phase angle
(IBPA) |
 = the mth vibrating blade mode |
 = the nth blade mode generating the pressure
oscillations |
At least one aerodynamic damping coefficient must be specified for each IBPA
(equal to the number of blades) while keeping 
and 
constant. If a value is not specified, the program writes an array value of
zero for both 
and 
. The values of 
and 
are relative to the modes computed in the required modal analysis.
The number of AeroScalar values must be equal to the number of
pressure modes (
from AeroSpecs). If the number of
AeroScalar values is greater than 1, the values must be entered
by defining an 
array (*DIM) and entering the array name in the
AeroScalar field. For a discussion of how
AeroScalar values are computed, see Scaling Aerodynamic Coupling Coefficients.
The value for nBlades should be equal to the number of sectors
of the system. If there are multiple blades per cyclic sector, then the combination of blades
on the single sector will have an aero coefficient value. In this case, each blade will not
have a distinct aero coefficient.