Cquad-to-Caero

Program translates MSC Nastran CQUAD4 elements with 1D CROD elements on leading edge to CAERO1 elements with generation of d2wgj, wkk and f2gj matrices.

Copyright (C) 2018 Wiśniowski Piotr

Theoretical details

Please read Static stability calculation of aircraft for explained usage of this software. Additionally read Dynamic stability calculation of aircraft for further reading regarding usage of results of this analysis.

Usage Example

Input model

Example of input file can be found in Example folder. This is basically any valid MSC Nastran aerodynamic input file (along with structural part) with some additional modeling tricks:

• All aerodynamic surfaces are modeled by using standard CQUAD4 elements on center surface.
  • All these elements must have same normal vector.
  • All these elements must have associated PAERO1 properties.
  • All these elements must have all grids which lie approximately behind front leading edge grids with CROD in the direction of flow.
  • Triangular surfaces must be modeled as CQUAD4 elements with single side edge length equal to 0.
• Leading edge of each aerodynamic surface must be meshed with CROD elements.
  • All these elements must have associated PAERO1 properties same as CQUAD4 elements from this surface.
  • All CROD elements numbering must be continuous across leading edge. This is in order to allow coefficient interpolation.
• For each leading edge (defined as first CROD element and last CROD element) additional aerodynamic profile coefficients can be supported:

| $DMI_INT | EID1     | WKK1     | WKK2     | F2GJ     | EID2     | WKK1     | WKK2     | F2GJ     |
| $DMI_INT | 10001460 |  1.43116 | -0.51663 | -1.50991 | 10001542 |  1.43116 | -0.51663 | -1.50991 |
	
	EID1, EID2		- First and Last elements between which interpolation will occur.
	WKK1, WKK2, F2GJ 	- Aerodynamic coefficients at EID1 and EID2.
	
Remark:
	Free and long field formats are not supported.

Result files

Several files are generated:

• .aero_bdf - file generated from input file with inserted CAERO1, SET2, AELIST, SPLINE6 elements and included .w2gj, .fa2j, .wkk files. This file is basically ready to be run under MSC Nastran.
• .w2gj, .fa2j, .wkk - files containing DMI cards with w2gj, fa2j, wkk matrices.
• .HVASCI - File used to visualize generated matrices in Altair HyperView or with some modifications in Partan.

Execute Parameters

Typical parameter values are set by default. Default values for parameters:

Values used by SET2 card for defining the prism containing the set for splining structural grid points to aerodynamic grid points:

SPLINEL = -0.1
SPLINEU = 1.1
ZMIN = 0
ZMAX = 0

Division of each CAERO1 to a number of aerodynamic grid points. Used for mesh size dependency validation:

NCHORD = 1
NSPAN = 1

SPLINE6 Nastran entry parameters:

DZ = 0 - Linear attachment flexibility.
FPS = FPS6 - Method for the spline fit. Either FPS3 or FPS6.

Typical usage:

Cquad_to_Aero.exe Whole_aero.bdf NSPAN=1 NCHORD=1

Contact

If You have any questions or problems contact me at [email protected].