aerocoeff#

SpecialPurpose.aerocoeff(aeromodetype='', aeromappedfilenames='', aerospecs='', aeroscalar='', nblades='', autofileread='', **kwargs)#

Computes the aero-damping and stiffness coefficients and writes them to an APDL array.

Mechanical APDL Command: AEROCOEFF

Command default:

No defaults are available for the aerocoeff command.

Parameters:
aeromodetypestr

Mode type to be used.

  • BLADE - Non-cyclic cantilevered blade mode (default)

aeromappedfilenamesstr

The description of the argument is missing in the Python function. Please, refer to the command documentation for further information.

aerospecsstr

Name of numerical array containing data organized to correspond to the AeroMappedFiles array. See the Notes section for specific information that must be in the array.

aeroscalarstr

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)

nbladesstr

Number of blades.

autofilereadstr

Key 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 Multiplier in CFD file) from CFD file header. The scaling values read will be used in calculations and the AeroScalar input will be ignored. The nodal diameter values will be used to cross check the value of i (input through AeroSpecs array).

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 Jobname AeroArray 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:

\[equation not available\]

where

  • \(equation not available\) = the i th interblade phase angle (IBPA)

  • \(equation not available\) = the m th vibrating blade mode

  • \(equation not available\) = the n th blade mode generating the pressure oscillations

  • \(equation not available\) and \(equation not available\) = 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 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 ), wherer 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:

\[equation not available\]

where

  • \(equation not available\) = the i th interblade phase angle (IBPA)

  • \(equation not available\) = the m th vibrating blade mode

  • \(equation not available\) = the n th 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

\(equation not available\) and \(equation not available\) constant. If a value is not specified, the program writes an array value of zero for both \(equation not available\) and \(equation not available\). The values of \(equation not available\) and \(equation not available\) 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 ( \(equation not available\) from AeroSpecs ). If the number of AeroScalar values is greater than 1, the values must be entered by defining an \(equation not available\) 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.