The GRAPE code (GRids about Airfoils using Poisson's Equation) is an elliptic
grid generator originally intended for isolated airfoils. The code was
written by Reece Sorenson at NASA Ames Research Center, and was modified
by Rod Chima at NASA Glenn to allow generation of periodic C-type grids
for turbomachinery blades. Turbomachinery grids generated with GRAPE can be used directly with the RVCQ3D CFD code.
- Axial compressors and turbines
- Centrifugal impellers and radial diffusers (no splitters)
- Linear cascades
- Isolated airfoils
- Supports all options in Sorenson's original code
The geometry input to GRAPE is completely general. If you can generate
coordinates for your geometry, GRAPE can probably put put a grid around
- C-grids around blades
- C- and O-grids around airfoils
Input and output
- Arbitrary specification of inner and outer boundary points
- Several options for reclustering boundary points
- Interior points are generated as a solution of a Poisson equation.
- Forcing terms in the Poisson equation maintain grid spacing and angles
at the boundaries.
- Version 107 uses new monotone splines for accurate geometry definition.
- Namelist input
- Airfoils are input in a Cartesian (x,y) coordinate system.
- Turbomachinery blades are input in a cylindrical (m,rbar*theta) system,
where m is the arc length along the surface and rbar is a mean radius.
- Grid files are written as binary data in standard PLOT3D format
- Grid files can be read directly by RVCQ3D.
- Minimal printed output
Computer and graphics requirements
GRAPE requires a Fortran 90 compiler and CFD visualization software for
use. Click the button below for more information.
Test cases included with GRAPE 107
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C-grid, NASA rotor 37,
70 percent span
C-grid, NASA 6:1
C-grid, Goldman annular
O-grid, Garabedian and Korn airfoil