AIAA CFD High Lift Prediction Workshop
Geometry and Mesh Generation Workshop
NASA High Lift Common Research Model (CRM-HL):
Test Article Definition:
A general description of the CRM-HL can be found in
AIAA Paper 2020-2771 (Lacy & Clark).
Specifically, the particular geometry definition
provided here represents the NASA 10%-scale
semispan CRM-HL test article, as tested in the QinetiQ wind tunnel in 2019
(AIAA Paper 2020-2770 (Evans et al.).
(Note that flap angles, gaps, overlaps, and slat height / gap were changed on the test article in QinetiQ
relative to earlier testing at NASA.)
Future CRM-HL wind tunnel models going forward will be designed and built according to a reference configuration geometry specification,
which is slightly different than the geometry used to design and build the NASA 10%-scale model.
The following geometry files for this configuration are provided in full-scale inches.
The geometry files are provided in both IGES and STEP formats.
There are three landing configurations included.
The first is the nominal configuration, with inboard flap angle of 40 degrees and
outboard flap angle of 37 degrees.
The second and third configurations have modified flap settings: one at 37/34 degrees, and the other at 43/40 degrees.
The slat is at 30 degrees in all cases.
The Test Cases for HLPW-4 are posted on the
Test Cases page.
- Nominal Configuration (inboard/outboard flap angles on 40/37 deg):
- Inboard/outboard flap angles of 37/34 deg:
- Inboard/outboard flap angles of 43/40 deg:
The V2 geometry is different from V1 in the following way. Pinch-points
(where a CAD face has a very cusp-like corner where two curves meet at nearly 0 degrees)
were adjusted on the flap-bracket connections to the flap underside, and on the outer WUSS end-wall.
The adjustment made the angle slightly more pronounced where the curves meet,
and this corrected some very slight overlaps detected between these curves as they approached the corner.
This fix helps avoid some grid generation issues and also helps to
insure consistency among all grids (many grid generators were found to require adjustments in these regions).
If you encounter any problems/issues as you build grids using the V2 geometry, please make your own
fixes, DOCUMENT everything done, and plan to share your fixes with the workshop committee.
Note that the geometry includes regions that may be very difficult to grid (and possibly solve),
including very thin gaps at the bottom/inside edge of the slats. These were present in the
wind tunnel configuration, so they were left in. It is up to you how to handle such areas;
this is part of the challenge of the workshop. Again, be sure to document every
assumption/change/fix that you make, as your grids are created.
NOTE: STEP files only support SI units. For the purposes of
this workshop, the subject model is in inches. The conversion based unit (#614316 in the file) should be used
by a STEP reader to convert the model on import. In this case, units of CM were chosen with a conversion factor
of 2.54 (again the STEP file includes this conversion constant). In the end, be sure to check that your final
size agrees with the numbers below (e.g., full-scale wing semi-span should be 1156.75 inches).
If possible, for consistency between grids,
it is recommended that the following geometry
definition for the freestream (farfield) boundary along with symmetry plane be used:
CRM-HL Boundary-Layer Tripping Information
from QinetiQ Test:
Geometric Reference Parameters for the NASA CRM-HL (full scale inches):
- Mean aerodynamic chord (MAC) = 275.8 in, located at y=468.75 in
- Use the MAC as the x-direction length to nondimensionalize pitching moment about the moment reference center
(see Q12/A12 on the FAQs page)
- Reference area of the semi-span model = Sref/2 = 297,360.0 in2
- Moment reference center (MRC): x=1325.90 in, y=0.0 in, z=177.95 in
- Wing semi-span (b/2) = 1156.75 in
- Aspect Ratio (AR) = b2/Sref = 9.0
- In the wind tunnel, the standoff did not contribute to forces or moment
If you are generating your own meshes for the CRM-HL configuration instead of using the
provided baseline meshes,
you should try to follow the gridding guidelines found on the
Grids page, and the final grids must be made available to the HLPW Committee.
QinetiQ Wind Tunnel Geometry Files:
Note that the
wind tunnel geometry has been scaled up to match the full scale CRM-HL geometry. I.e., the
tunnel is being represented as 10 times its actual size.
When the tunnel geometry is loaded together with the CRM-HL full scale geometry, the model
is positioned appropriately in the tunnel test section, at zero degrees angle of incidence.
Instructions for rotating to a different angle of incidence are included in the pdf file below.
(The rotation centerline is parallel to the Y axis at X=1227.5, Z=198.0.)
Note that using full scale CRM-HL geometry may require adjustments to the fluid
properties in order to match Reynolds number; as with the free air cases, adjusting the kinematic viscosity is the
preferred approach (see Q10/A10 on the FAQs page).
An alternate approach would be to scale the entire geometry set by 0.10, and run with real air
(X,Y,Z) Tunnel Probe Locations (full-scale-model inches):
- TempProbe 1: (-6467.3414, 2121.9242, 1096.6220)
- TempProbe 2: (-6467.3414, 2121.9242, -700.6220)
- TempProbe 3: (-6467.3414, -543.4989, 1096.6220)
- TempProbe 4: (-6467.3414, -543.4989, -700.6220)
- PTprobeTip: (-6388.1923, -965.9338, 1847.6063)
- S3Static (Max): (-4873.4423, -1043.0073, -1737.6408)
- S1Static (Noz): (-2102.6710, 1636.0441, 198.000)
- BL Rake: On floor at (X,Y,Z) = (54.2717, -35.000, -152.2203),
with Y range from -35.00 to 35.8662 inches
Typical CFD Iterative Procedure for Running in the Wind Tunnel:
(This method is sometimes automated. See, e.g.,
- Use inviscid thermodynamic relations with the desired reference Mach number (Mach=0.2) to obtain total pressure (Pt) and total
temperature (Tt) (relative to the reference static pressure and reference static temperature, respectively)
at the tunnel inlet. Apply an appropriate inlet BC that fixes these total values; this inlet BC remains unchanged throughout the iterative procedure.
- Set static pressure BC at tunnel outflow boundary. (A typical starting value might be slightly lower than that
required for an empty tunnel; see
AIAA-2017-4126 for an example in a different wind tunnel.
In the QinetiQ tunnel geometry, the area ratio between the test section and downstream boundary
is approximately Amin/Aexit = 0.474.
An estimated starting back pressure for the provided QinetiQ tunnel configuration is
Pexit/Pref ≈ 1.02.
- Run CFD solver.
- Use temperature (average of 4 probe locations), pressures, and total pressure computed by CFD at the tunnel probe locations,
along with the tunnel calibrations (described in above Q5m_Tunnel_Modeling_V01.pdf file) to calculate q/Pt and Mach in the CFD run.
Note, in an empty tunnel, the computed Mach should also be achieved (seen) at the tunnel's
calibration reference location ((X,Y,Z)=(1227.5, 791.7717, 198.00) in the provided scale).
However, when a test article is present in the tunnel, the computed Mach value is based on the calibration only.
- Iterate steps 2-5 until the computed Mach is within a desired tolerance (preferably within 0.195 - 0.205);
i.e., if the computed Mach number comes out too high, then raise the back pressure, if too low then lower
the back pressure. You may need to experiment to determine the effect, and use linear interpolation to determine
the next back pressure to try (for example, if p_back1 yields M1 and p_back2 yields M2 (and neither M1 nor M2 is
close enough to the goal of M=0.2), then try
p_back = p_back1 + [(0.2 - M1)*(p_back2 - p_back1)/(M2 - M1)]). Note that this iterative procedure can take time.
Once converged, other conditions, particularly Re, should also be
checked using inviscid thermodynamic relations.
- Note that the required back pressure may be different for every case (it could be affected by the grid and the angle of incidence of
the model in the tunnel).
Note: one can solve for the flow in the tunnel using the
tunnel coordinate system fixed (rotating the model to different angles of incidence),
or using the airplane coordinate system fixed (rotating the
tunnel around it). If the latter method is used, be sure to also rotate all of the Tunnel Probe Locations.
Other Geometry Files:
Some of the TFGs are making use of other
geometries beside CRM-HL as part of their research for HLPW-4. These include:
- 2-D Multielement Airfoil based on CRM-HL
- NASA Juncture Flow Model F6-based wing and body with horn/leading edge
extension (Tests 640 and 653))
- NASA Wall Mounted Hump Model
Please check periodically for updates, and/or get on the email distribution list by request to
to be notified directly of any updates/changes.
Link to: Grids Page
Link to: Test Cases Page
Return to: High Lift Prediction Workshop Home Page
Recent significant updates:
02/18/2021 - Added estimated starting back pressure setting for in-tunnel iterative procedure
01/25/2021 - Added Tunnel Probe Locations and typical CFD procedure for running in tunnel
12/18/2020 - Added QinetiQ Wind Tunnel geometry files and information
12/17/2020 - Added clarification regarding use of MAC as the length to nondimensionalize the pitching moment
11/18/2020 - Added link to NASA wall-mounted hump website
10/20/2020 - Added additional suggestions in red regarding problems/issues
10/13/2020 - Posted V2 geometry files and farfield/symmetry plane definition
09/25/2020 - Added tripping information from QinetiQ test
09/24/2020 - Added links to other geometry files
09/09/2020 - Updated note regarding STEP file details
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Last Updated: 05/21/2021